Questions on Air Conditioning on 1979 928

More
29 Jun 2011 22:06 #5323 by EWM
After one week of ownership the A/C quit cooling in the 1979 928. Listed below are three questions.

I found a pool of oil on top of the receiver/dryer sight glass. After soaking up the oil, I tried tightening the sight glass with a hex wrench. The sight glass easily tightened about 1/3 of a full revolution. The top of the entire receiver dryer is covered with oily residue.

1. Does anyone think tightening the sight glass will prepare the system for a recharge? I do not see oily residue on other A/C lines or components but I do not (ahem) have a clear view of every thing under the hood. The compressor was replaced and the entire system renewed 5 years ago but the car has been driven very little the past 4 years before I bought it. By very little, the battery went bad and less than one tank of gasoline was consumed. The A/C system was cooling well a few days ago and there has not been any traumatic event like a sudden discharge of freon.

2. Can any competent A/C shop recharge the system or do I need to find a Porsche specialist?

3. The electric fan does not immediately start when the A/C is turned on. The fan does come on from temperature at the second mark with the A/C on or off. Is this normal or does some relay or switch/sensor need replacement?

Thanks for any help. Some fine day not too far in the future all the minor problems with this wonderful car may be resolved. Then the only fun remaining will be to drive it.

EWM
1979 928
5 speed manual

Please Log in or Create an account to join the conversation.

More
30 Jun 2011 01:25 #5330 by srshaw3
Any competent A/C shop should be able to service the 928.

What electric fan? A '79 would have a belt/viscous drive fan for cooling. Are you referring to the HVAC blower? I would think it should come one whenever turned on, as it is used for heat as well.

Please Log in or Create an account to join the conversation.

More
30 Jun 2011 09:05 #5339 by EWM
There is an electric fan that blows through the A/C condenser mounted in front of the radiator.

The belt driven clutch fan is behind the radiator.

Please Log in or Create an account to join the conversation.

More
30 Jun 2011 09:57 #5342 by srshaw3
Sorry, it has been a while since I have looked. You are correct that would be temperature actuated. I hear mine most often running when in traffic or when I first turn the car off. When the car is moving, there is sufficient air flow that it is not required. (as I recall).

Please Log in or Create an account to join the conversation.

More
02 Jul 2011 19:32 #5375 by N2O-928
Hi, yes the electric fan for the A/C is not active when the A/C is on, it only comes on for three reasons.
1. The A/C dryer temp gets hot (that is the fan temp switch on the top of the dryer) the switch on the side of the dryer is the low-pressure switch to disable the A/C system when low on Freon.
2. The Water Temp is too high, temp switch on left lower front side of rad.
3. Intake temp too hi (intake temp switch).

edit: you can test the fan by removing the connections on any of these switches and connect them together.


Yes a good A/C shop should be able to do it, however I would chose an A/C shop that works on "special" cars.

Please Log in or Create an account to join the conversation.

Moderators: Rich928mm928billvvOC

Don't have an account yet? Register Now!