user 783003

Don't know where to start...

Brought the car in to have it charged, or at least leak checked. They said that it held a vacuum, but when they tried to charge it, the compressor wouldn't engage. They bypassed the control unit and engaged the compressor manually, but it still wouldn't take a charge.

Other electrical problems of note are the fog lights, when I replace the fuse and turn on the fog lights, the fuse trips instantly - not sure if they're related, but thought I should mention it.

timatt

Are you certain that they are introducing the gas into the low pressure side of the compressor? I believe that it is the shrader valve that is furthest to the rear of the car. (I don't have my C4 here so I can't look to verify). I've never tried to introduce the gas into the high pressure side ( the valve facing the passenger side of the car) so I don't know what would happen if that were tried.



BTW: I'm fairly close to you. I work in North Webster.

Tim
'89 C4

user 783003

I brought it to the local independent that the local PCA guys recommended. They partner with a local A/C shop for the charging/leak testing. To answer your question though, I have no idea if they did the right side. Other than understanding the basic principles of refrigeration, I am clueless with this part of the car.


Had to look up North Webster as I'm not originally from here and am horrible at Indiana geography. Ever do any of the Michiana PCA events?

timatt

I'm not an A/C expert, but something doesn't seem to add up. Do you know whether there was any freon in the system before they pulled the vacuum? Did you get any cold air at all? Did the compressor run before they pulled the vacuum? Seems like if they were able to suck something out, they should be able to put something back in. I would think that the pressure differential between the vacuum and the freon tank would allow enough gas into the system to at least pressurize they system to the same pressure that is in the freon tank.

Tim

user 783003

It's never worked since I got it in '08. Don't know any of the other answers.

gr1275

It sounds like they appied 12V directly to the compressor clutch. If it would not take a charge something sound clogged... I'd replace the dryer and expansion valve. Also check the high/low pressure switch. Put in the proper amount of oil and pull a vaccum.
Good luck... let us know what the eventual solution is.

Gary

jimq

be sure the small wire that goes from the compressor towards the right rear corner hasnt come out of the connector

user 783003

That wire is connected. When I turn the A/C on, I don't get 12V to it. I disconnected it and ran a jumper from the fuse box to that wire and the compressor kicks on. Any thoughts as to why I wouldn't get voltage there?

Also, some fan of some sort kicks on and off in the front left wheel well. It goes on for 5 to 10 seconds and off for the same amount of time. This only happens when the snowflake button is depressed. What is this fan and what is its function?

gr1275

Matt,
That's the fan for the condensor and sounds like it is functioning as normal. As for voltage on the compressor, have you checked all the associated fuses?

Gary

user 783003

What fuses do I check?

How can I test the relay in the back?

CraigC

I think GR1275 may be onto the problem. I had a plugged receiver drier on mine and it would take a small amount of freon 134A and then because there is a pressure relief valve ahead of the receiver drier and downstream of the compresser it would open and vent the rest of the charge. I thought I had a huge leak in my system. Turns out I just needed to have someone look at it that knew what they were doing (Ruf in Dallas) My understanding is the receiver drier is basically a filter and it is not uncommon for them to get plugged on old cars (all kinds, not just Porsches). Im blowing cold again which is a good thing because we have already hit 112 deg this year.

user 783003

Dryer and Expansion valve P/N's? High/low pressure switch?

Oil?

I'll be doing a few more searches now.