No AC, fans and compressor OK, what next?

Nobody wants to give me a 0% loan to buy a new car, so sounds like my A4 will be around for awhile. And being voluntarily isolated for the duration of the current pandemic, I'm getting bored enough to fix the air conditioning on my '03 Golf with manual AC that quit cooling a few years back. I've been able to verify that the two fans come on, and while I can't see for sure, the RPMs drop by about 50 for a second when I turn the AC on, so I suspect the compressor is at least producing some drag.



I've read the pinned AC diagnostic thread, anything else I should check before I break open the piggy bank and buy some AC guages, etc.?


Thanks in advance, Diana

see if the large AC hardline (low pressure) gets cold after a minute, if so, you may have a blend door missing foam issue or a blend door control lever issue. If the low pressure pipe stays ambient check to make sure the compressor is indeed turning. If it's turning the compressor's internal variable displacement valve may be faulty. If not turning, clutch could be faulty or faulty wiring to the clutch. Another thing that happens to the mk4's is the clutch nut loosens and falls off followed by the clutch pressure plate.

I've never worked on AC before, so please bear with me. I assume you mean the larger of the 2 lines that goes through the firewall, and it's at ambient temperature.

gearheadgrrrl said:

I've never worked on AC before, so please bear with me. I assume you mean the larger of the 2 lines that goes through the firewall, and it's at ambient temperature.

Click to expand...

yes, make sure compressor clutch is intact and turning.

If it isn't, try turning it by hand.

If you decide you need gauges get some new service valves at the same time.

VW's, at least the few I've seen, have leetle black rubber hemispheres that tend not to survive connecting the gauges. They look like balls from the outside when you take off the caps but they aren't.

I just had an 03 beetle that the pressure switch was bad. The fan would only work on 1 speed and not both.

I unplugged the electrical connector to the sensor and it started blowing freon out of the sensor. Never had that happen before. Replaced the pressure switch/sensor and vacuumed/recharged the system and it works now.