73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: cwilson jr on June 24, 2013, 06:43:50 pm
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started working on getting my a/c running. never have used it in the 7 years ive owned the truck. all of the components are there. i just installed the belt and now i'm troubleshooting. nothing happens when i use the hvac controls inside. i started with the low pressure switch and when i jump it, it turns on.
1. so, i'm going to obviously get a new switch first, but when it kicked on i noticed the compressor pulley did something. i'm not sure if it locked up, it seemed like the belt was still moving, but there seemed to be movement in the pulley and tension placed. does the pulley engage and disengage and just get tighter when u turn it on? makes sense, i just want to make sure this is normal and don't want to worry about snapping a belt.
2. after i replace the switch, what would be my next steps? i would imagine pull a vacuum using the air pump from harbor freight i see ppl using on here and then convert and fill with ref. and dye and check for leaks?
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What year truck are you working on? As far as operation, the 73-75 systems were a bit different than the 76-up system. What refrigerant are you going to be using? These trucks originally came with R-12, but that is usually expensive (unless you have a source who stocked up). Has the truck been converted to use R-134 at some point and was it correctly done?
Since you say you are jumpering the low pressure switch (i.e., cycle switch on low pressure side), I presume it is a 76-up variety. The compressor clutch should engage whenever the switch is bypassed and the control panel in the cab is switched to a/c. If you have low refrigerant levels, the compressor should not engage even when everything is connected normally. As for the belt question, you should check the compressor belt tension to verify that it is tight.
If the truck had been converted to use R-134, usually (but not always) there will be the R-134 to R-12 adapters threaded onto the R-12 fittings on the system.
You may not need to replace the compressor cycle switch if your system is low or out of refrigerant. If you don't know what refrigerant and oils were placed in your system (i.e., is it still setup for R-12 or was it switched at some point to R-134 or something else), it would be a good time to have all the old oil and contaminants flushed out of the entire a/c system (condenser, evaporator, lines, etc.).
Since the a/c system hasn't been serviced in a long time, it also would be prudent to replace the accumulator/drier to ensure that you don't have premature failure once everything is back together and running.
Once everything is cleaned and a new accumulator is in place and proper amount and type of oil in place for desired refrigerant: Use a set of gauges and pull a vacuum on the system and completely evacuate all air. Turn off the valves and let the system set with vacuum. Watch the gauges when you turn off the valves and write down the vacuum. Wait around an hour, go back and check the gauges. If there is no change in recorded vacuum and vacuum level after 1 hour, then you can begin to charge the system with refrigerant.
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this is on an 85. r-12 system. when i first had gotten the truck i remember placing the 134 adapters on and tried adding ref. to no avail. it wasnt important then, so i never thought anything of it again, until now, where i would like to get it working for my disabled son. i have purchased a new cycling switch and accumulator as of now, along with the following tools:
http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html
http://www.mastercool.com/media/91046A-Parts%20List.pdf
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If it is low on refrigerant the compressor won't cycle, so it may not be your switch. Years ago I just added Freeze-12 to mine (you can still find it on ebay) to get it to function and it cooled just fine for quite a while. To fix it right you will need to pull it all apart and flush everything, replace the orifice tube and the accumulator. I would take the compressor off and drain the oil from it. Then you could add the correct amount of oil to the system. If you are going to go r134 changing the condenser to a parallel flow type (probably less than $100) will improve cooling in my experience.
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i have done everything you said except for switching condensors, which sounds like a good idea, but i have to wait on that and i didn't pull the compressor. I already have everything flushed and put back together ready to vacuum. now, the 134 conversion kit i have has a can of oil included in it. at this point i don't want to really pull the compressor out unless it was absolutely a necessity.
after flushing the lines, cond. and evaperator, should there be enough oil still in the system or should i add the can of oil entirely, or partially?
i also noticed when i pulled the lineset off the rear of the compressor, it was bolted in correctly, but without any gaskets. i purchased an o-ring set, but to me if there was to be gaskets there, they would have to be flat, so i left that as i found it for now.
update: just evacuated the system and began to install ref. in. once the compressor kicked in, the belt started squealing and smoking. is my compressor bad?
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How much refrigerant was put in when the compressor started squealing? If it was just a couple of cans, then yes I think the compressor may be locked. On the other hand if you were nearly at a full charge it may indicate that the pressure in the system was too high--may need to set a fan blowing on the condenser or wet it with water, which will reduce the system pressure; or you could be overcharged. Not sure about the gaskets on the compressor, but mine did have an o ring type gasket between the compressor and the hose manifold. There is probably about 1 or 2 ounces of oil in the compressor. I don't remember how many total for the whole system on our trucks. You can get a wrench from auto parts stores that will turn the compressor, so you could take the belt off, let the system cool down and find out if you can turn it. I'm no expert, just trying to help.
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i have put about 3/4 of a can i would say in there. basically i stopped adding ref. as soon as the compressor kicked on and i noticed something wasn't right.
so, i'm thinking the compressor is locked from what i'm reading. if i have to replace the comp. as its looking more like, what do i do about ref. and oil now?
currently i am thinking about recovering the ref. i already put into the system, into an empty flush kit canister i have to salvage it, if thats possible or disposing of it entirely. i know to fill the back of the new comp. with oil, so i would imagine that would take care of those two things. if i'm right? would i be alright from there or do i have to evacuate again?
i just paid to have it evacuated. i have the $20 harbor freight air vacuum pump, but havent messed with it yet.
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With the engine off: Can you turn the compressor (not just the pulley) by hand?
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just inspected everything with the engine off. the compressor doesn't turn, the pulley doesn't turn, the whole assembly is secured to the bracket all the way around tightly, and the belt is tight. amazingly the belt still looks to be in good shape.
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Will it turn without the belt on it?
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nope, she was locked up, replaced and we're good to go.
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now, only when the compressor engages, there is a "vibration" in the belt. the belt starts bouncing, maybe up to an inch. i'm concerned my belt will eventually break while using the a/c. the only thing i notice is the power steering may be sitting ever so slightly on a slant.
i have the belt tight along with the compressor brackets.
is that normal for the power steering? anyone have an idea of what would cause this?
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So there is an alignment problem with the belt? Are you missing brackets? It will probably throw it before it breaks.
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its ever so slight, but that's the only thing i'm noticing. have all of the brackets, i confirmed this and everythings tight. if the ps is the cause. is there a way to align it? if it threw the belt, wouldn't it be chopped by the belt?
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now, only when the compressor engages, there is a "vibration" in the belt. the belt starts bouncing, maybe up to an inch. i'm concerned my belt will eventually break while using the a/c. the only thing i notice is the power steering may be sitting ever so slightly on a slant.
i have the belt tight along with the compressor brackets.
is that normal for the power steering? anyone have an idea of what would cause this?
The vibration you described sounds normal. Four pulses per revolution are generated by the A/C compressor and imparted to the belt; the pulley spacing causes the belt to resonate at low RPM. It was a design shortcoming. You may need to tighten the compressor belt a little bit more.
...have all of the brackets, i confirmed this and everything is tight. if the ps is the cause. is there a way to align it? if it threw the belt, wouldn't it be chopped by the belt?
Can you post a pic of the 'belt alignment' issue?
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well, i got a longer bar for leverage and managed to get the belt even tighter and so far it has made a difference. now, i'm going to see if it will stay that tight.
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that didn't last too long. the ac quit working today. popped the hood and the belt is sitting on the pulley sideways. i see cracks so my belt is shot again and i wonder if it rolled from the slight slant thats on the ps pulley. i'm going to try and get some pics posted tomorrow.
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here is what i noticed with the compressor and power steering pulleys being off-set. also, you can see how the belt rolled as well.
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any ideas? if this is the power steering causing this and not the compressor, is there a way to re-align it?
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your compressor is misaligned with the pump.. you have to move the compressor back about 1/4 of an inch or so... you can do this with washers as if they were shims... leave the pump the way it is, if you move the pump you will misaligned it from the engine... and dont tighten it too much because you put extra stress on the belt...
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any ideas? if this is the power steering causing this and not the compressor, is there a way to re-align it?
Misalignment of the A/C compressor is fairly common with the compressor mounting configuration you have. You need to establish the plane in which the A/C compressor is misaligned, and then determine how skew that plane is with the correct plane of the water pump & power steering pump.
Place a straightedge along the flat, backside of the compressor pulley, so the straightedge extends first toward the water pump pulley and then toward the p/s pump pulley. When the compressor pulley is properly aligned the straightedge will be parallel and coincident with the back of the w/p pulley and the center ridge of the p/s pump pulley. How far off is it? Realignment often requires varying amounts of change at the three compressor mounting points (i.e., compressor lower pivot, left outboard adjustment, and top inboard adjustment).
I just completed this exact same realignment on my A/C compressor, so I will do what I can to guide you through it.
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i tried several different things along with different washer and bolt combos, no matter what i did i could not get the compressor to back up like i needed. there was just no room left on the lower rear bracket. the one that goes down to the exhaust manifold
before i got your post, i took it down the road to a guy that i deal with sometimes and has a shop and he said the issue is not in the power steering pulley, because it aligns with everything else and said the same thing i had found out, it needed to be moved back and there wasn't room. he looked up some things and it turns out there are the same r4 compressors with different pulleys. i had purchased the first one listed below that was for an 85, which was the same one that i removed originally.
NOW, keep in mind my 85 truck originally had a 305 and someone dropped in a 350 a long time ago, BUT the locked compressor i pulled off originally matches up to the one i ordered the first time. obviously, not the correct pulley in the truck originally though.
SO, to continue, he found the same compressor with a pulley that has the belt track further back, which is listed for 80-84s. i have this one posted in the second link.
originally on truck and installed exact replacement and the one i'm having a pulley alignment issue:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1985-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ijkpwZ91sgi?itemIdentifier=328559_147281_3515_
now ordered this one and hopefully this'll do the trick:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mgZ91sgi?itemIdentifier=162909_147353_3515_
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ok, so, i have a mess on my hands. i'm going to give you what details i know and see if anyone has had a similar issue or knows about these subtle differences.
i have an 85 k10 with a 350, originally a 305. was purchased this way. i purchased a replacement a/c compressor which matched the old one installed already that was locked. there was no belt installed. this the compressor in the first link:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1985-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ijkpwZ91sgi?itemIdentifier=328559_147281_3515_
it look liked the #1 picture below, installed. obviously you see the aftermath, but you get the picture with the alignment.
then i purchased this compressor:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mgZ91sgi?itemIdentifier=162909_147353_3515_
which was pretty much the same result, except misaligned on the other side. picture #2.
is there a pulley thats in between these two, or are there wrong pulleys on the motor? everything, but the ac compressor is in line. there seems to be so many differences in the r4 pulley types and from year to year? we have tried different things with washers and bolts and it only misaligns things worse.
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The AC belt goes around the rear pulley of the PS pump. My 85 is somewhat off as well. It seems to be smack dab in the middle of the double pulley. I run the 7 series belt which so far has been OK. It is not right but at least it works. I don't know the answer to this either.
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The 305 and 350 small blocks should use the same compressor for any given year/model. The vehicle probably had the wrong replacement compressor installed when you acquired it.
Although a 1987, my compressor mounting (i.e., brackets and belt configuration) is similar to yours and it aligns perfectly after minor shimming (see image). I use this Everco/Four Seasons compressor P/N 58235 (http://www.autozone.com/autozone/parts/A-C-Compressor/_/N-91sgi?filterByKeyWord=58235&fromString=search&isSearchByPartNumber=true).
Measure the distance between the machined front face of the aluminum compressor body and the back of the steel pulley, near the top of the belt groove. The 58235 compressor body-to-pulley distance measures 1.125". Would that bring your belt into alignment?
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bd,
would you happen to have or be able to send me additional pics? i'm taking this back in and it would be great if i could have one showing the shims and also the entire compressor with all related brackets to guide us if we need it.
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Using a straightedge to establish a starting point and estimate the extent of misalignment between the compressor to water pump pulley and the compressor to power steering pump pulley. Measuring the distance between the compressor body and the rear flange of the clutch pulley. Rear compressor bracket for comparison.
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The 1/8" thick one-piece spacer installed on the compressor top bracket. The spacer sandwiches between the backside of the bracket and the cylinder head to rotate the inboard mounting of the compressor forward. I chose a one-piece design so I could permanently secure the spacer in place using a socket head bolt. Two 1/8" thick washers would have worked just as well. The compressor bracket has a stepped mounting surface that requires a matching step in the spacer. The extra 1/8" thickness of the spacer required a longer Grade 8 flange head bolt. Since I run aluminum heads, I was able to increase bolt penetration an additional 1/4". The thickness of shim selected will be unique to every engine.
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Following installation of the top bracket with its 1/8" thick spacer, compressor alignment with the water pump was significantly improved, but needed some additional tweaking to make it perfect. However, compressor misalignment with the steering pump was still too far rearward. After reevaluating with the straightedge, it was evident the top outboard edge of the compressor needed to move rearward about 1/8", which effectively would rotate the bottom of the compressor pulley forward, bringing the compressor into alignment with the steering pump while at the same time nudging the inboard edge of the pulley forward into perfect alignment with the water pump pulley. In gradual stages, I removed about 5/32" of height off of the outboard, top rear adjusting bolt (the stacked bolt-in-a-bolt passing through the compressor body), rechecking the belt alignment constantly. I intentionally removed enough material to install a Grade 8 washer between the stacked bolt and the rear support bracket to improve clamping of the slotted adjustment (the gold colored washer in the image).
Essentially, your compressor uses a three-point mounting. The lower bolt is the pivot point; there is no slotted adjustment at the pivot. Hence, I left the pivot unchanged and used that as a constant reference. The remaining two attachment points useful for compressor alignment are where the upper bracket bolts to the engine and where the compressor body fastens to its rear bracket at the adjusting slot.
As you make changes, take your time and observe how the plane of the compressor pulley shifts in relation with the water and power steering pumps. Adding spacers is trial and error. Shimming too much is easy to correct. But, if you need to "remove" material, removing too much material is more of a challenge to rectify. Be patient. Think through any changes before you commit to them.
Edit: spelling
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thank you, this should get us moving in the right direction.
i believe i have all of the brackets, but i did notice in your first pic in the last post, it appears there is a bracket in the upper rear that bolts to the intake manifold? not the support rod, but a seperate bracket or a section of one? i'm not sure, so i included a pic of everything i have. could you tell me if i'm missing something?
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The compressor rear bracket (left brkt in your image) mates with the power steering pump bracket (not shown). The small bracket at the left front of the intake manifold is the factory lifting eye (pictured below in its entirety). Two 1.5" long bolts fasten it to the intake and one through-bolt & nut attach it to the upper compressor bracket to help anchor the compressor.
The R4 generates enough vibration, amplified by the standing wave that develops in the V-belt, that procuring or fabricating the missing manifold bracket, in my opinion, is important. Otherwise, the upper compressor bracket is anchored to the engine by only one 3/8" diameter bolt and the 1/2" X 11" long bracing rod.
The missing intake bracket is made from 3/16" thick mild steel. All bolts should be Grade 8 - flange head preferred. Don't compromise with bolt length; arrange for the greatest penetration into the cylinder head casting as possible. Condition the bolt holes with a 3/8" X 16 bottoming tap to ensure maximum use of the depth of the holes. Apply torquing compound or other lubricant to all of the bolt threads, except the second-back intake bolt, which should be coated with Teflon paste thread sealant or #2 Permatex.
I'll be checking in periodically over the weekend, if there are additional questions.
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Old thread but great info here. Helped me out alot.