A/C compressor or something cheaper?

[dr.tb.xc]

It's hot and humid where I live. Though air condidioning may be optional in some parts of the world, it's essential here six months out of the year.

That said, I need help. My A/C has become unreliable, and I'm uncertian where the problem lies. It will work perfectly for a while, then abruptly begin to blow warm (ambient temp.) air. Occasionally this will happen at normal driving speeds, but the problem is more likely to appear when the vehicle is idling in traffic. The problem ALWAYS appears after a door or window has been opened for a few moments, as if loading the cabin with warm, humid air is more than the system can handle.

The only way to get the system to begin functioning again is to power-off the vehicle for a time. Simply switching off the A/C for a while doesn't seem to help.

I've had the refrigerant re-charged and double checked with little or no affect. This problem began last summer, but having the refrigerant topped-up completely solved the problem until this year. Obviously, there is a slow leak somewhere in the system, but it will hold pressure well, so I don't think that's the problem.

Thoughts? Suggestions? Am I looking at a dead/dying compressor, or could the problem be more affordable to repair? If it is the compressor, what years/other Volvo models will have compressors which are compatible with mine (2.4L)? I have no inclination to fork over $1,200 to have the local dealership replace a failed compressor. If the compressor is to blame I'll find the youngest (used) one that will fit, replace it myself, and have the system refilled at a local repair shop.

Should the serpentine belt be replaced when the compressor is replaced?

-Todd

[Phrog]

I'd suggest a bit more trouble-shooting before replacing the
compressor. It could possibly be a thermostat (I believe there
are at least 3 in the cabin compartment). Several years ago,
strange cabin heat/cool behavior in my 2001 XC turned out
to be a failed thermostat.

[starfish]

This problem does not sound like a bad compressor at all. My best cyber-guess would either an electrical problem with a sensor or actuator. This will have to be diagnosed by the dealer using the VIDA to read out codes. You can check to see if any codes are stored in the system yourself but you will not be able to tell the exact code. Turn the ignition key to position II and press and hold the "read" button on the turn signal stalk while tapping the rear fog button twice. The car will tell you that it is checking for DTC's. "Reading" or "checking" on the display is okay. If a DTC is stored it will tell you. Cycle the message display to each module by tapping the "read" button again.

[Willy]

Although it is probably not a DIY job, leaks can be traced by means of a fluorescent agent and UV lamp, see attachment.
Willy

[XCSwedie]

Make sure the little vent/fan in the climate panel is clean/free of dusty deposits.

[dr.tb.xc]

Make sure the little vent/fan in the climate panel is clean/free of dusty deposits.Yes, I've already pulled out the climate control module and assured that the fan, sensor, etc are free of lint, dust, or other debris. Good thought, though. I've also had the system tested with fluorescent dye--no significant leaks were detected.

Also, starfish & Phrog, I'll take your advise and have the local dealership evaluate the issue with VIDA. In the mean time I'll try Phrog's suggested method to see what codes may be stored in the system.

Thanks for all your input. I'll watch the thread to see if anyone else has any further thoughts/suggestions. I won't be ordering a replacement compressor yet.

-Todd

[Art]

Then again, it could be just the A/C system reacting normally under certain conditions. The A/C compressor is controlled by the ECM (engine control module) and it determines when the compressor operates. If any of the following conditions are met, the compressor is disconnected:

1) High engine coolant temperature
2) Wide open throttle
3) The engine has just been started
4) Overpressure in the A/C system

The ECM can delay compressor activation such as in a situation where the idling speed needs to be compensated for a heavier stress load.

[dr.tb.xc]

Then again, it could be just the A/C system reacting normally under certain conditions. The A/C compressor is controlled by the ECM (engine control module) and it determines when the compressor operates. If any of the following conditions are met, the compressor is disconnected

1) High engine coolant temperature
2) Wide open throttle
3) The engine has just been started
4) Overpressure in the A/C system1) Coolant temp reads normal.
2) Throttle at idle; problem still there.
3) Problem never present until engine has been running for a while.
4) Same issue before and after refrigerant serviced.

Also, when the problem crops up the vehicle has to be powered off for a bit before A/C will function again.

Still, I suppose it could be an ECM issue. Hopefully I'll have an answer later this week after I have it checked at the Volvo service dept. I'll keep you all posted.

-Todd

[ifnt420]

I had the same problem last month; Exact same symptoms as you described.
The culprit was a faulty Temp Sensor near the evaporator.
Part No. 30665118. Price US$40 parts, and Labor US$10.
Now, all is okay.

Might worth a shot at checking that, much much cheaper than a new A/C compressor. :D

[dr.tb.xc]

I had the same problem last month ... The culprit was a faulty Temp Sensor near the evaporator. Part No. 30665118. ... Might be worth a shot at checking that, much much cheaper than a new A/C compressor. :DIf you're right (and maybe even if you aren't) you may just be my new best friend! I'll mention you (and the part number) when I visit the service rep this week. If I'm ever in Taiwan I insist on buying you a drink. [happy] Sadly, the chances of my ever being in Taiwan are essentially nil.

I pity the XC owners out there who haven't discovered how amazingly helpful this forum can be.

-Todd

[ifnt420]

Goodluck and keep us posted!! [thumbup]