A/C Clutch Not Engaging (or only seldom) - Warm air blowing

[DrJeff]

My car is R-12 and stock setup for A/C (with R134a ports on so I can use my R134a gauges). The gauges read low port high pressure at rest (engine not running) and then down around 40 when engine running and Max A/C on. While the High Port is reading zero during rest and while running (I think the port is not connecting correctly - the R134a port adapter just sits on top of the R12 port, so the gauge quick disconnect may not be opening the valve).

When the car is started and the Max A/C selected, the fan and clutch engage for about 3 seconds. The fan and clutch don't re-engage for perhaps another 45 seconds to a minute.

Here is a video taken with the gauges connected and the Max A/C on. At 52 seconds you can hear the clutch engage and the fan come on for about 2 seconds.


http://www.youtube.com/watch?v=XWm-LX9v-jU

13499

It was cooling well for 4-5 months, but I noticed it not cooling as well this last month. Now it doesn't seem to be cooling at all.

Any ideas?

Thanks
Jeff

[Bitsyncmaster]

You need to get that high pressure reading. Those cheap aluminum adaptors sold in car parts stores are not made very good and I bet it does not press the valve in. Try another adaptor on the high side.

Best to order the steel adaptors sold at AC parts shops.

[Ron]

I agree...I run across the aluminum adapters all of the time...if that is what you have try tightening it down a bit more if you don't think it is at the limit...If, when removing the high side connection, there was obviously no pressure, I would try pushing down firmly on the connection before releasing the lock...sometimes a good test (but a poor solution, of course).

fyi It is normal for you to get the rest pressure you are seeing, even if the refrigerant is quite low, especially after it has sat in your area...it could be low (my wild guess so far, but I wouldn't add any) or anything as simple as the mode switch contacts flaking out...

[lindbergh]

Ignoring your gauges, one possibility would be your low pressure switch turning your compressor off. If that is the case either your low pressure switch is bad or your A/C is very low on refrigerant. It would help if you had readings on your gauges that were accurate. Your A/C is hardly on to be indicating a normal low pressure as would an operating A/C and no high pressure, the two pressures should be about equal with A/C off. Without good readings it's hard to diagnose but another possibility is a broke or stuck low pressure or high pressure valve on the compressor.

[David T]

If it was running OK and cooling well and now it isn't and the clutch and fans are not cycling as they should you don't need a gauge set to know you have lost refrigerant and the low pressure switch is not allowing the system to run. If you still have the original hoses they should be replaced. Otherwise you should be looking for leaks at each connection with some soapy water while you pressurize the system. I would start testing with the service ports. Get rid of those adapters otherwise someone may shoot some -134 in there!
David Teitelbaum

[DrJeff]

You need to get that high pressure reading. Those cheap aluminum adaptors sold in car parts stores are not made very good and I bet it does not press the valve in. Try another adaptor on the high side.

Best to order the steel adaptors sold at AC parts shops.

You're right about the high side port adapter, the valve is not being activated by the quick release connector. I'll need the steel connectors and a high side connector that is about 1/8 to 1/4 in shorter.