a/c compressor

[p_dyer]

I've never changed an a/c compressor. How difficult is it?

[volkerc]

Originally Posted by p_dyer

I've never changed an a/c compressor. How difficult is it?

as easy as changing an alternator. take off the belt. take out the 2 bolts that hold the alternator in place.disconnect any electrical connection. and remove the a/c lines. be a bit careful not to break those. make sure to replace the old o-rings with new ones (r134a compatible).make sure to fill in some a/c oil into the new compressor, by filling in from the back and turning compressor by hand.

[p_dyer]

Do I have to get the system bled? Is oil put in w/ the freon then as well?

[HotZ28]

If you are changing from R12 to R134a you need to change the oil to a ester oil. Look at a service manual to determine how much oil is required. You usually just put enough in the compressor to do an initial lubrication then inject the rest with the refrigerant. You can buy both non pressurized and pressurized ester oil at your parts store. If you already have a 134a system you need to follow the same procedure for adding ester oil.

Listed below is the EPA law on recvovery, however if you don't have any freon in the system, you can ignor these requirements.

RECOVERY REQUIREMENTS
During service or dismantling of motor vehicle air conditioning systems, containment of the refrigerant is
mandatory. Never open a system without first following proper recovery procedures as set forth by SAE J1989 for CFC-12 and SAE J2011 for HFC-134a. The following procedure will serve as a guideline to refrigerant recovery, always operate the recovery equipment according to the manufacturers' recommendations.
Connect the recovery equipment to the vehicle system service ports. Operate the recovery unit to remove the refrigerant until the system has been reduced from a pressure to a vacuum. With the recovery unit shut off, wait at least 5 minutes to determine if all refrigerant has been removed. If the system returns to a positive pressure, indicating that there is still refrigerant left in the system, additional recovery is required. Repeat the recovery operation until the vehicle A/C system vacuum remains stable for 2 minutes.

[se2bsw]

Hi there, i too have a 92 pa and im trying to figure out what the trouble is with the ac. when i turn on the ac the air is not cold like ac temp should be, however it is not blowing hot air either thinkin it would be hot if no ac system is workin). is there a way to test the ompressor to suure its not working?.also i just did a conversion to 134from the 12, and my question is is the low line, were thethe ac goes in, is it actually the one closest to the rad, or the one by the tank,by fire wall. if is it the one by the rad, than i need to find a adapter for the inline as the conversion kit i bought doesnt come with one. i would appreciate any feed backk. tyvm in advance.

[HotZ28]

First, the low side line where you install the refrigerant, is the one going to the accumulator/drier “tank” near the firewall. The high side line on an “ R-12” system in the 1992 Buick takes a special fitting and is usually not included with the cheaper “conversion kits”. You can still get by without using the high side fitting, if you know how to read the low side. Low side should read around 28-32 psi on a stable system, at 80-85 deg. ambient. Also, somewhere in this process, it would be wise to change the high side fitting so you can measure the compressor high side pressure.

When you did the conversion, did you evacuate the system and flush out the old “mineral” oil? Also, did you evacuate the system prior to adding the R-134a and did you add the correct amount of POE or PAG oil in the system? If not, you have a problem that will eventually kill your compressor, if it has not already. The proper flush, evacuation and recharge procedure must be followed, or the system will not cool as expected and also will suffer a premature death!!

A/C systems designed for R-12 have a heavy weight (usually 525 viscosity) “mineral” oil which circulates with the refrigerant and provides lubrication for the compressor. For a system to function properly, this mineral oil must be “miscible” (dissolve in) the refrigerant being used in order for it to return to the compressor properly. R-134a has zero miscibility in mineral oil, so newer oils (mostly PAG and POE) have been developed for R-134a systems. If an R-12 vehicle is retrofitted to R-134a (the oil changed to PAG), sometimes the PAG oil will fail from existing chloride deposits (which cannot be flushed out) from the previous R-12 in the system. POE oils also have their problems, one being low lubricity and another being poor stability (breaks down easily and very moisture sensitive).

[se2bsw]

Hi hot thanks for the feedback, i now know were to put the free on..the fitting closest to the firewall, which today i checked for freeon, and there was nothing. My understanding is that the ac compressor(clutch) WONT run unless there freeon in the system.i was skepticle at first butafter a few test were the guy took the black "power" wire of the switch on the tank and shorted it out, the compressor clutch actually worked!. he did this twice, and both times it worked. if you put the wire back on the tank the compressor did nothing. just wanted to confirm this is actually the way the compressor will come on, with freeon only in. tvm in advance.

[HotZ28]

Originally Posted by se2bsw

Hi hot thanks for the feedback, i now know were to put the free on..the fitting closest to the firewall, which today i checked for freeon, and there was nothing. My understanding is that the ac compressor(clutch) WONT run unless there freeon in the system.i was skepticle at first butafter a few test were the guy took the black "power" wire of the switch on the tank and shorted it out, the compressor clutch actually worked!. he did this twice, and both times it worked. if you put the wire back on the tank the compressor did nothing. just wanted to confirm this is actually the way the compressor will come on, with freeon only in. tvm in advance.

That is right; it will usually turn the compressor on if you jump the low side switch. You are also right to not run it without refrigerant. The "Freon" is what circulates the oil and if it does not circulate, you will kill the compressor.
If the system is empty, you must have a leak that you need to locate and repair. You can inject a can of R-134a with dye, to help you find the leak. You still need to evacuate the system after the leak has been repaired. Also, this would be a good time to install a new drier and orifice/screen.

Do it right the first time, or you will pay for it later!

[se2bsw]

Originally Posted by HotZ28

That is right; it will usually turn the compressor on if you jump the low side switch. You are also right to not run it without refrigerant. The "Freon" is what circulates the oil and if it does not circulate, you will kill the compressor.
If the system is empty, you must have a leak that you need to locate and repair it. You can inject a can of R-134a with dye, to help you find the leak. You still need to evacuate the system after the leak has been repaired. Also, this would be a good time to install a new drier and orifice/screen. Do it right the first time, or you will pay for it later!

Hey thanks for the good news..thought the compressor was dead!!! one last thing, the air coming in from inside wether it be on warm/cold is the same temp and its not blowing very much at all. i thought i read something about a coloured sensor on the firewall, could this make a difference. tyvm in advance again.

[p_dyer]

I took my car to a local shop and the problem was the switch. I got one from a junkyard. Fixed it.

[se2bsw]

Originally Posted by p_dyer

I took my car to a local shop and the problem was the switch. I got one from a junkyard. Fixed it.

hi p_dryer, do you happen to know were that partivcular switch is...? also does anyone know of that particular coloured switch thats on the firewall, or is it the same one, that your referring to. tyvm in advance.

[HotZ28]

Originally Posted by se2bsw

Hey thanks for the good news..thought the compressor was dead!!! one last thing, the air coming in from inside wether it be on warm/cold is the same temp and its not blowing very much at all. i thought i read something about a coloured sensor on the firewall, could this make a difference. tyvm in advance again.

I assume that you have auto climate control (ACC)? If you do, does the temp stay the same, no matter what temp you select? Also, can you feel any change in air movement when manually moving fan speed up or down? There is a "sun sensor" on the dash that has an affect on air flow through the vents on the ACC system, if that is what you are referring to, however, it is not likely to be your problem though. How long have you had this car and did this problem just appear recently?

[se2bsw]

Originally Posted by HotZ28

I assume that you have auto climate control (ACC)? If you do, does the temp stay the same, no matter what temp you select? Also, can you feel any change in air movement when manually moving fan speed up or down? There is a "sun sensor" on the dash that has an affect on air flow through the vents on the ACC system, if that is what you are referring to, however, it is not likely to be your problem though. How long have you had this car and did this problem just appear recently?

Hi hot, as for the first question, no theres really no change in the temp whether its on cold/warm. as for the second question, theres very little change in the flow of air even on hi. ive had this car bout two years, but this is first time ive attempted to use the a/c. tyvm in advance....

[HotZ28]

Have you followed the previous advice on finding the leaks, evacuation, oil and charging the system? If so, is your compressor cycling normally? Lack of air flow can be due to a restriction in the evaporator or the blender door actuators sticking or being out of calibration.

[p_dyer]

I replaced the control module on the inside of the car. It didn't look like it could be fixed to me. Thats why you want to get one from a junkyard.