Changing AC Compressor

kirkeric · 07-18-07, 08:16 PM

Hello all,

I just joined a couple days ago and appreciate all the notes. I have a 1987 corvette coupe.

The AC doesn't work and I already attempted to recharge it and the compressor does not kick in. At this point I am assuming it is the old compressor.

I've seen a decent deal for about $150. for a new one and I'm pretty handy. So my thoughts are I get the current system emptied out, remove the compressor, install new one. Or so it seems.

I'm confused on what the "high" side is used for since it has a valve but we are always told to NOT mess with it.

Can anyone offer pointers on properly replacing the compressor?

Thanks,

Eric

bradfordsvettes · 07-18-07, 09:59 PM

you need to check the low pressure cycling swicth first. just because the compessor does not engage it does not mean it is bad you will need to do some electrical diagnostics before canning the compressor you need to see if the clutch and electrical components are ok just my 2 cents steve

kirkeric · 07-18-07, 10:48 PM

Thanks. Appreciate the feedback. Now to identify this low pressure switch. Can you help with that? Is there anything visible that I should see in this switch?
Thanks.
eric
[ QUOTE=bradfordsvettes;832416]you need to check the low pressure cycling swicth first. just because the compessor does not engage it does not mean it is bad you will need to do some electrical diagnostics before canning the compressor you need to see if the clutch and electrical components are ok just my 2 cents steve[/quote]

bradfordsvettes · 07-19-07, 10:06 PM

it is on the accumulator next to the heater box it is an off on switch you could check it with an ohm meter should be closed with a full charge you need to get a wiring diagram to complete you diagnosis my guess is the commpressor is probably ok just need to do some home work Steve

lagasvd · 07-20-07, 02:06 AM

If I were you I would find a reputable mechanic and have them diagnose and fix. It can be expensive to have repaired but worth it to have it done right the first time. The compressor went out on my 86 convertible and I have an excellent mechanic. When you replace the compressor you need to also replace the dryer/accumulator and should replace the expansion valve at a minimum. There are other small parts that should be replaced while you have the system open. Your system is probably running R-12 refrigerant, which is not readily available
now (some places still have some leftover) so your system will have to be converted to R-134, which means replaceing some other things and adding a different lubricant. Other than not being able to buy the refridgerant unles you are licensed and probably not having the right tools (gages, hoses, vacuum pump, etc) to correctly evacuate and recharge the system correctly warrents hiring a certified, honest, and expert A/C man to do the work. To replace the compressor (along with all the other parts needed), completely evacuate and recharge the system (with R-12) and fully test and guarentee the parts and work cost me $450. I thought this was a bargain since I've had ice cold air now for over three years. Just my two cents worth.

Robertwav1 · 07-20-07, 07:12 AM

Quote:

Originally Posted by lagasvd

If I were you I would find a reputable mechanic and have them diagnose and fix. It can be expensive to have repaired but worth it to have it done right the first time. The compressor went out on my 86 convertible and I have an excellent mechanic. When you replace the compressor you need to also replace the dryer/accumulator and should replace the expansion valve at a minimum. There are other small parts that should be replaced while you have the system open. Your system is probably running R-12 refrigerant, which is not readily available
now (some places still have some leftover) so your system will have to be converted to R-134, which means replaceing some other things and adding a different lubricant. Other than not being able to buy the refridgerant unles you are licensed and probably not having the right tools (gages, hoses, vacuum pump, etc) to correctly evacuate and recharge the system correctly warrents hiring a certified, honest, and expert A/C man to do the work. To replace the compressor (along with all the other parts needed), completely evacuate and recharge the system (with R-12) and fully test and guarentee the parts and work cost me $450. I thought this was a bargain since I've had ice cold air now for over three years. Just my two cents worth.

I agree with this. Unless you have a thorough understanding of the AC, it shouldn't be messed with. Even charging tricks are incorporated on a system that's low. If any air at all is introduced into the system through improper charging, the gas is no good. It's a very technical field and there are laws with stiff fines for venting gases. Please consider this. I've been doing AC for 30 years now and it still scares me. Pressures are dangerous and can blind you. Read about it, work alongside of a mechanic in the field for a while and then you will be ready to properly diagnose and get a system up and running again. Safety first!

gmjunkie · 07-20-07, 07:49 AM

Quote:

Originally Posted by Robertwav1

I agree with this. Unless you have a thorough understanding of the AC, it shouldn't be messed with. Even charging tricks are incorporated on a system that's low. If any air at all is introduced into the system through improper charging, the gas is no good. It's a very technical field and there are laws with stiff fines for venting gases. Please consider this. I've been doing AC for 30 years now and it still scares me. Pressures are dangerous and can blind you. Read about it, work alongside of a mechanic in the field for a while and then you will be ready to properly diagnose and get a system up and running again. Safety first!

I agree here!!!Wrong Place at the Wrong Time, You'll have a Dog leading you around!!!!!Refrigerant Will Freeze your Eye Ball's in a NY second!!!!!!

bradfordsvettes · 07-20-07, 05:59 PM

I agree with all the above statements. if he is at all handy he can still check out the electrical end of it just because the compressor does not engage it does not make it is bad and if the cycling switch is bad it can be changed with out emptying the system. saftey is first when fooling with refrigerant Steve

fatboyreyn · 07-20-07, 08:48 PM

if you are going to replace the compressor yourself, you have to evacuate the gas, reclaim if possible, replace the dryer and compressor, then pull a vaccum on the system for at least 1 hour. recharge with 134a. your new compressor will be compatible with both gasses. Make sure to put the correct amount of oil in the compressor before installing it. Oil can be purchased at auto parts store and is also compatible now with either gas. that guy who had his system converted for $450 got a great deal. Most mechanics,( and I use that term loosly) charge twice that and do a **** poor job. But then I don't trust anybody but me to work on my cars. The high side carries liquid freon and should not be bothered with. High side fittings are used to check the balance of system, using guages, and the home mechanic doesn't have to use the high side

bradfordsvettes · 07-20-07, 10:00 PM

the high side pressures should always be checked to make sure the system is operating correctly and that the cooling fans are doing their job high side pressure out of spec is sure fire death for a replacement compressor Steve

gmjunkie · 07-20-07, 10:01 PM

Quote:

Originally Posted by fatboyreyn

if you are going to replace the compressor yourself, you have to evacuate the gas, reclaim if possible,

It's the Law, Dude!!

Quote:

Originally Posted by fatboyreyn

replace the dryer and compressor, then pull a vaccum on the system for at least 1 hour. recharge with 134a. your new compressor will be compatible with both gasses. Make sure to put the correct amount of oil in the compressor before installing it.

I didn't see anything here about Flushing the system,Replacing the Orifice Tube (for 134a),O-Rings(for 134a) or Distributing the oil in equal portions to Condenser,Dryer and Compressor!!

Quote:

Originally Posted by fatboyreyn

Oil can be purchased at auto parts store and is also compatible now with either gas. Most mechanics,( and I use that term loosly) charge twice that and do a **** poor job. But then I don't trust anybody but me to work on my cars.

Didn't see anything about adjusting the Low presser switch down to 21 lb cut off,or replacing with a switch for 134a if it non adjustable,or using 10 % less refrigerant! 134a really should be weighed in,1 oz to much or 1 oz to little the system will not work properly and can freeze up on a Hot Humid day!

Quote:

Originally Posted by fatboyreyn

The high side carries liquid freon and should not be bothered with. High side fittings are used to check the balance of system, using guages, and the home mechanic doesn't have to use the high side

They should,unless there doing a **** poor job like your loosely termed mechanics you were talking about!!

bradfordsvettes · 07-20-07, 10:07 PM

you are 100 percent correct JUNK lots to be considered but the question is why isn't it engaging steve

jerseydevil · 07-22-07, 05:20 PM

remove the wireing from the low pressure switch, jump the wire with a paper clip or pc. of elec. wire. while the motor is running this will override the LPS, and allow you to fully charge your system, ( i set mine at 40psi and it works fine. ) after chargeing ---reatach the wireing to the LPS, The system charges quicker while its engaged... Good Luck