A/C troubleshooting

[doclees]

Just had the A/C in the 93 atx converted. Mechanic manager said it was blowing cold after conversion with no seen leaks. I picked it up the next day and the wife took it. Later that day she runs the a/c with no cold air. I check it that night and the compressor clutch is not engaging. Fuse ok. Isn't the a/c also controlled by the CCRM? If it is how do I test this to trip the compressor?

thanks

 

[Lupo]

Just had the A/C in the 93 atx converted. Mechanic manager said it was blowing cold after conversion with no seen leaks. I picked it up the next day and the wife took it. Later that day she runs the a/c with no cold air. I check it that night and the compressor clutch is not engaging. Fuse ok. Isn't the a/c also controlled by the CCRM? If it is how do I test this to trip the compressor?

thanks

Check to see if there is any pressure in the system. if you don't have a gauge, you can always buy one of those R134 refill cans or kits that has a gauge on it.
Your R134 may have leaked out.
If you still have a charge:
Check the low pressure switch. you can simply jump this switch to engage the clutch. WARNING: only do this if you are SURE you have a charge in the system.
On rare occasions, this switch goes bad, and needs to be replaced.
If you have charge, and you jump/bypass the low pressure switch, but AC clutch does not engage, try hooking the AC clutch to direct power. Again, only do this if you are sure you have a charge.
If after connecting the clutch to direct power, it still does not engage, either your field coil is bad (the electro magnet that engages the clutch), or the gap on your AC clutch is bad, and you'll have to remove a shim to make the gap closer.

 

[SHO#7]

Or you can just jump the low side switch. If that kicks the compressor, you more than likely have a leak in the system. The pressure switch prevents the compressor from turning on. The freon has much needed oil in it also. No freon, no oil, no compressor, no ac.

Just only jump the switch for a second.

Mike

 

[projectSHO89]

I've also seen intermittent coil to harness connectors. In fact, I had to repair that on my current 94 several years before I bought it.

Did the shop add a high pressure cut-out switch as part of the conversion? They should have. If so, it is added in series with the cycling switch and is another potential electrical problem.

Step 1 is ALWAYS checking to see if there is enough charge in the system (min 50 psi) to close the pressure cycling switch. Jumpering the switch can tell you that the problem is one of two things: Either the switch is bad or the charge is low. A gauge will tell you the difference.

If there is power at the switch AND sufficient charge. the problem will be either the CCRM module, the clutch (open coil or excessive gap), or the interconnecting wiring and connectors.

If the clutch is suspect, check the air gap. If over .035", perform a shimectomy.

If you haven't diagnosed it with this information, let us know and we'll provide pinpoint procedures based on your reports.

Steve

 

[turbo79]

I'm having similar issues; my system shows pressure (near 100 lbs.), but no cooling is happening. Can anyone tell me how/where? one can jump the low pressure switch?

 

[projectSHO89]

I'm having similar issues; my system shows pressure (near 100 lbs.), but no cooling is happening. Can anyone tell me how/where? one can jump the low pressure switch?

You have a reasonably well-charged system.

Locate the accumulator. It's either buried down next to the radiator (driver's side) or under the cover at the firewall on the passenger side depending on year and tranny.

The switch is on the top of the accumulator. Just unplug it and insert a paperclip into the harness connector to test. If the clutch now engages, replace the switch - about 10-15 bucks at any parts store. It just screws out and the new one back in. A drop or two of PAG oil on the o-ring is recommended.

Steve

 

[turbo79]

You have a reasonably well-charged system.

Locate the accumulator. It's either buried down next to the radiator (driver's side) or under the cover at the firewall on the passenger side depending on year and tranny.

The switch is on the top of the accumulator. Just unplug it and insert a paperclip into the harness connector to test. If the clutch now engages, replace the switch - about 10-15 bucks at any parts store. It just screws out and the new one back in. A drop or two of PAG oil on the o-ring is recommended.

Steve

My SHO is a '92 (obviously an MTX). I will look for the accumulator and try the "test." What does the accumulator look like?

 

[doclees]

This has been continued here http://www.shoforum.com/showthread.php?t=90942. It was an Accumulator line leak.