Author Topic: 87 AC repair, replace, or convert for a guy thats never worked on AC  (Read 219 times)

Offline shinkle

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New to the forum and looking for direction from those with experience.  Summer is coming so I need AC in the south.

I recently bought a 1987 R10 5.7l from a local original owner estate sale. The Harrison R4 AC compressor is locked up. If I turn on the AC the belt squeals.  I don't see refrigerant leaks and I pressed the nipple on the dryer and gas escaped, so I think its still charged.  What should I do?  Replace the compressor and recharge with R12.  Replace the compressor and dryer and recharge with R134.  Replace everything and recharge with 134.  Something else?

I've seen kits with compressor, tube filter, oil, o-rings, dryer, but I'm not sure how to verify I buy the right kit?

I've never worked on an AC but I've read alot about flushing the system, youtube videos, replace orifice tube filter, replacing dryer.  It looks like alot of it is straightforward bolt on, but I know there has to be more to it.

What would you do?
1987 R10 5.7L TBI

Offline Mr Diesel

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #1 on: February 20, 2021, 10:29:38 AM »
Dont bother recharging with R12. It was better refrigerant, but is now so expensive it's not worth it. Spring one tiny leak in your 34 year old system and it leaks out hundreds of dollars in refrigerant. WalMart has R134 for about $5 per can and you only need 3 or 4. There are even other cheap options like air duster propellant (Walmart), or EnviroSafe (propane with the sulfur removed).

If you replace the compressor with another R4 unit I recommend brand new, not rebuilt. Another option is Sanden conversion. I would put a new dryer in and at least clean the orifice tube. I wouldn't bother with any flush. Just blast compressed air through with the system open and pull a good vacuum before you charge it.

Internet searches will show you everything you need to know about conversion. Been done a million times already.
1976 C20 Crewcab, 6.2L/SM465
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1983 C30, 6.2L/TH400
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Offline VileZambonie

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #2 on: February 20, 2021, 03:40:32 PM »
Do not use alternate refrigerants or other gases, please. Either find someone who can reclaim and recharge R-12 or retrofit to R134a. Find out what the shop you will be using wants to do as some shops don't even have a means of reclaiming R12 anymore.

If the compressor failed, then the system likely has debris in it and therefore you should replace the compressor, orifice tube & accumulator. You will need to flush the system out good and replace the o-rings, use the correct oil for the refrigerant you decide on.
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Offline shinkle

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #3 on: February 20, 2021, 07:13:22 PM »
Thanks for the info
1987 R10 5.7L TBI

Offline shinkle

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #4 on: February 22, 2021, 03:00:40 PM »
A little more info that may change things.  The compressor has the belt on it and actually turns just fine until I  turn on the AC.  That is when it freezed and belts squeals.  Does this mean the AC clutch is the problem or is it the entire compressor shot?  I was thinking I might could get by just replacing the clutch without opening the system.
1987 R10 5.7L TBI

Online werewolfx13

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #5 on: February 22, 2021, 04:40:21 PM »
the belt turns fine with the AC off because the clutch is doing its job and not turning the compressor. When you turn on the AC, the clutch engages and tries to turn the seized compressor.
Chris
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Offline bd

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #6 on: February 22, 2021, 08:38:37 PM »
A/C compressors impose a significant belt load.  Perhaps the belt is too loose.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline MIKE S

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #7 on: February 22, 2021, 09:03:22 PM »
If the compressor shaft has a nut on it put a socket on it and try to turn it in a clockwise direction. If you need to replace it I would recommend a new ac/delco. There are some minor differences in pulley groove placement on most replacement compressors that can make the pulley not be aligned. I had to go back to the original listing in the paper GM catalog and find the original part number and find the the current part number which is 15-2026. That is for an 87 350 tbi.

Offline bd

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #8 on: February 22, 2021, 09:33:17 PM »
I disagree on tightening the compressor shaft nut.  The nut sets the gap between the clutch and plate.  Tightening the nut on some compressors can close the gap to the point that the compressor will experience excessive clutch drag that will overheat the clutch and the adjacent pieces or never fully release.  With the engine off, the compressor hub can be grabbed by hand and rotated.  There may be a significant drag but it should turn.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline shinkle

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Re: 87 AC repair, replace, or convert for a guy thats never worked on AC
« Reply #9 on: February 23, 2021, 06:48:54 PM »
Great, thanks again for responding.  It sounds like the compressor is the problem so I plan on replacing it and converting to 134a
1987 R10 5.7L TBI

Offline 75gmck25

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When you shop around for compressor, see if you can find a source for an R4 direct replacement, instead of buying a rebuilt R4.  R4s are an old design, and rebuild quality is iffy.  I know there are adapters that allow you to use the stock A6 lines with a newer Sanden compressor, so I assume there is something similar for the R4. 

Make sure you also replace the accumulator/drier and the orifice, and use A/C flush to completely flush out the the evaporator, condenser, and lines.  Then you can switch to using PAG oil, which is what is used with nearly all new systems.  Get a package of the new O-rings (green?) and lightly lube them with PAG when reassembling.  You will also need a set of conversion fittings that adapt old R12 fittings to the R134a charge hoses. 

Then vacuum the system for 30 minutes, and initially charge to about 75% of the recommended R12 charge (for example R12 says 48oz, then R134a would be 36oz).  Use the gauges and vent air temps to determine if you need a little more R134a to get good cooling (it often does).  There is no sight glass anymore to look for bubbles, so keeping track of pressures is the key.

Bruce