Cost to convert my AC system to R134a

[got2haul]

My truck has an aftermarket in-dash-style air conditioning system, that is still using R12 as the refrigerant.  I went to a local highly-recomended automotive AC shop to get an idea what its going to cost to convert it to R134a, since my current system leaks out all the freon in about a year.  To install crimp-style hoses, a new dryer, a new compressor (mine's leaking oil), and labor, I was quoted $800.  This was only for the underhood stuff.  He told me it would be an additional expense to change the hose ends on the underdash side of the system since he'd have to drop the underdash components to change those hose ends, but that could be skipped if I didn't want to go to that additional expense.

What do you think?  Price sound about right?

[Lt.Del]

Some would say you should replace the dryer, two taps, condensor, evaporator under the dash, compressor, orifice tube and perhaps hoses. You must flush the system with flushing agent and preferrably us a air compressor.  

At a minimum, I'd replace the two taps, one high pressure, the other, the low pressure tap. I'd also replace the dryer and orifice.  Personally, that's all i'd replace and it only takes a few minutes.  You must flush the system with flushing agent and preferrably use a air compressor if nothing else is changed out. Hook up the manifold guage and a vacuum pump to vacuum the air in the system, then open up the valve for the r134a and have fun.

Many would say to replace the compressor, evaporator and condensor at the same time.  that is where the money comes in.  If your system is old, and I guess it would be if you are converting from the old freon, go ahead a replace those, but, I'd be tempted to try the inexpensive parts mentioned above first then see how she does.
It is a pain to replace the evaporator though.  

Being the redneck I am, I wouldn't replace the compressor, evaporator and condensor unless the forementioned procedure resulted in problems.    If it is not to your satisfaction, you really only have a $30 dryer to replace if you open up the system again, ok, and a $3 orifice tube and the 3 cans or so of R134a.

You should find your leak though...when you get the oil to put in the compressor (if you replace the compressor), get the green dye stuff and you can tell where any leak is located.

[VileZambonie]

Is this a TXV system? Do you know if it has a receiver dryer or an accumulator? How bout some pix for some better advice.

[choptop]

$800 isnt bad. I was quoted $1500 for the compressor, filter and recharge on my 86 GMC. Im gonna look at getting certfied to do A/Cs. I have enough vehicles of my own to justify the cost.

[VileZambonie]

It's $15 bucks to get certified to handle refrigerant. You can probably find a used AC machine cheap. I make BANK doing AC service.

[choptop]

Thanks Vile, my father in law has a recovery system that Im sure he'd led me use since he doesnt need it much. Im definately looking at doing it.

[got2haul]

Is this a TXV system? Do you know if it has a receiver dryer or an accumulator? How bout some pix for some better advice.

Sorry, Don't know what TXV means.  Here are some pictures.  The first is the dash control unit.  Second is the compressor and I assume accumulator (?).  The third is a closeup of the accumulator or dryer, or whatever it is.  And the last is a couple of hoses coming from the firewall that hook up to these components.  Please excuse the dirty engine/engine bay.  Since the truck is running good, I focused my initial efforts on the interior and exterior.  A new motor is coming eventually, and the engine bay will get cleaned up then.

As you can tell, I know squat about AC units.

[VileZambonie]

That's a TXV system (thermo expansion valve) It utilizes an expansion valve that has a capilary tube on the outlet side of the evaporator to control Evaporator temperature and refrigerant pressure drop. The aftermarket systems like that use barrier type hoses with lousy hose clamps. Go around and tighten all the clamps and check for any noticeable leak points.

Is there any refrigerant left in the system? If so have it recovered. Install the conversion fittings. Vacuum the system for at least 30 minutes. Ensure the systemholds a vacuum. Measure the amount of oil that came out of the system or just put in 4 oz of Ester oil with a UV dye. Charge the system with 80% of the original charge. It should be on a label somewhere. If not I can post a good pressure chart for you. It's easy enough to do and no need to flush the system.

[ibpauly]

There is a ton of mis-information out there about the conversion from 12 to 134. Most is wrong.
The difference between an r-12 compressor and a 134? The oil.

Change the oil in the compressor, change the drier (aytime you open the system, change the drier-cheap insurance), get a couple of charge port adapters. flush the system. Use nitrogen to push the flush through. Shop air too often has moisture in it.You may find one or two of your hoses leak with 134.  Replace this hoses if that is the case. Also, it is possible that your condenser may not have the capacity, since it is the old tube and fin style. You can replace that with a universal multiflow condenser. Go with about a 14x20 inch. Plenty of capacity. I sell them for less than 100 bucks, so if you get quoted 300 and up, shop around. They are buying them from the same place I am.

I've been in this business since 1976, and when the switch started happening in 1990, most people(even the professionals) really didn't know what was necessary. There was a lot of arguing on what needed to be changed and what didn't.

[VileZambonie]

ibpauly,

It is hard to say that  "most is wrong" Every circumstance will be different and should be analyzed as what's necessary and what is just simply wasting money.

A/C - Retrofitting R-12 Vehicles to R-134A
Notes

SUBJECT:
RETROFITTING R-12 VEHICLES TO R-134a

MODELS:
1994 AND PRIOR YEARS, PASSENGER CARS AND TRUCKS WITH R-12 A/C SYSTEMS

There has been a great deal of information presented by the media regarding the need to retrofit vehicles produced with R-12, to a substitute refrigerant. This bulletin will outline GM's position and future plans on this subject.

Most important, there is currently NO requirement to retrofit any R-12 vehicle. Vehicles built with R-12 can be serviced with R-12, as long as the refrigerant is available. At some point in time, R-12 may become either too scarce or too expensive to economically justify service on some vehicles with R-12. By that time, GM will provide you with instructions on retrofitting those vehicles from R-12 to R-134a.

GM vehicle divisions, platforms, and component suppliers have been actively working on the details of retrofitting R-12 vehicles. An enormous amount of work is required to determine how hundreds of vehicle models can be satisfactorily retrofitted. Additional information will be provided as it becomes available.

The following items contain important technical information that should answer many of the questions, and correct some misconceptions reported in the media.

SUBSTITUTE REFRIGERANTS

R-134a is the only approved substitute refrigerant that GM recommends and it should only be used if a complete retrofit procedure has been performed. None of the other refrigerants currently being marketed as replacement or drop-in substitutes for R-12 are approved for use in GM vehicles.

R-12 and R-134a are not interchangeable. R-134a cannot be added to fill a low R-12 system. The combination of the two materials can cause high system pressures, which could cause damage to the system.

Retrofitting an R-12 vehicle to R-134a requires careful preparation to insure that neither the vehicle nor the A/C service equipment has become contaminated.

RESIDUAL MINERAL OIL

The concern that mineral oil is chemically incompatible with R-134a and/or PAG lubricant has been proven to be untrue. A normal charge of mineral oil left in the A/C system after a retrofit to R-134a will not damage the system. Mineral oil, however, does not mix well with R-134a, and will not provide adequate lubrication. Tests on both the orifice tube and TXV systems show that the mineral oil parks in places such as the accumulator, and does not appreciably affect performance or damage the system. The retrofit service bulletin will specify the correct oil to be used. It is important that this oil recommendation be followed carefully.

RESIDUAL R-12

Residual R-12 left in a system, due to improper retrofit service procedures, may result in system damage unless the residual R-12 is kept below the 2 percent limit specified by the Society of Automotive Engineers' Specification J-1661. New service methods are being developed to minimize the level of R-12 remaining in the A/C system after the retrofit procedure is completed. Following these new procedures will be critical to insure that the above limits are met.

SYSTEM FLUSHING

R-11, a material commonly used as an A/C system flushing solvent, has been found to be chemically incompatible with PAG lubricant. Technicians should be aware that residual R-11 remaining in an R-12 system will be very damaging if the vehicle is retrofitted to R-134a later in its life. For many years GM has recommended the use of in-line filters as an alternative to system flushing.

SYSTEM FLUSHING, USING EITHER R-11 OR ANY OTHER FLUSHING MATERIAL, IS NOT APPROVED BY GM FOR ANY A/C SYSTEM.

DESICCANT PROTECTION

It has been reported that the desiccant (moisture absorption material) used in 1992 and older R-12 A/C systems is incompatible with R-134a and PAG oil. The older desiccant was designed specifically for R-12 systems, but testing has shown that it is NOT necessary to replace the older desiccant just because the vehicle is being retrofitted to R-134a. 1993 and newer GM vehicles use desiccant designed to be compatible with both R-12 and R-134a systems.

The amount of desiccant used in most GM vehicles is designed to last for at least seven years. To help maintain adequate protection for vehicles that must be retrofitted, it is recommended that the accumulator/dryer, which contains the desiccant, be replaced if the vehicle is more than five years old.

"O" RINGS

While continuing to service with R-12, be sure to use "O" rings and seal materials which are compatible with R-134a and PAG oil. This practice will eliminate concern in case the vehicle requires retrofitting later in its life. All "O" rings and seal materials available from GMSPO are compatible with R-134a systems.

RETROFITTED SYSTEM PERFORMANCE

Currently, it appears that for most GM vehicles, the retrofit procedure will require minimal changes to the existing system. Some vehicles may need additional parts and/or procedures to provide acceptable performance and/or durability. Our testing has shown that vehicles that have undergone recommended retrofit procedures will, in most climatic conditions, be minimally affected in terms of A/C performance.

SERVICE POLICY

Basic service policy is as follows:

During Warranty - If an R-12 produced vehicle A/C system must be repaired or recharged under warranty, repairs will be completed using R-12. If R-12 is unavailable or unaffordable, GM will notify the dealer body and will pay for the warranty repair and the retrofit to R-134a.

 NOTE: It a customer requests that an in-warranty vehicle be converted to R-134a, and the R-12 system is functioning properly, the customer will be expected to pay for the retrofit.

Out of Warranty - The cost of the conversion will be the responsibility of the customer.