2004 Jetta AC

My AC just blows hot air. It’s fully charged and was taken to a mechanic who said they couldn’t figure it out and to take it to the dealership. If it’s not super hot outside it will blow warm air so it’s bearable. But when it’s really hot outside it’s just hot air.

I don’t know if this is related but I my check engine light keeps coming on and then goes off for a few days. I was told the code said it was something to do with the coolant system. But I have no leaks and it doesn’t overheat.

It could be related. If the engine is running hot, the computer turns off the compressor in some cars, so as not to make things worse.

There is not enough info to even make much of a wild guess. One unknown is whether or not the A/C compressor is engaging.

If the assumption is made that the compressor is engaging and that the refrigerant level is fine then the suction hose should be cold and the discharge line should be hot.
Other unknowns are the high and low side pressures. And who says the system is fully charged; you or the shop?

1 Like

Me and the shop. They told me they checked everything they could think of. I know lots of people have had problems with VW AC so I was seeing if anyone had suggestions before I take it to a dealer

It’s just weird because they claim everything they checked worked and it started throwing codes. But like I said it doesn’t overheat.

I know it has been five days, but what were the codes?

Checking the fuses is the first thing I’d do.

Based on what the OP posted, I think that this is not fuse-related.

If a mechanic couldn’t figure out a blown fuse situation, that would be a very sad commentary on his diagnostic skills. And, at least the fuse for the HVAC blower is obviously intact.

It almost sounds like the system might be generating a tiny bit of barely cool air based on the original comments which also included (paraphrased) nothing but hot air on a hot day.

I alluded to whether the compressor was engaging along with system pressures and those were not answered. The OP says that the system is fully charged based on both his and the mechanic’s opinion. I’m not buying anything until those unknowns are answered.

A couple of years ago a neighbor asked me to look at an A/C issue on a Tacoma. It was said to be fully charged. Gauges showed a 60 PSI static reading so “fully” was not applicable at all.

So it will blow a tiny bit of cool air if I’m on the freeway. Or if it’s a mild day out it will blow cooler air. But it isn’t a lot and if it’s super hot out it’s useless. It’s been charged and when you hook it up to charge it it says it’s full. The mechanics supposedly ran a bunch of things and checked a bunch but couldn’t figure out why it wouldn’t work. The code was a engine coolant system not working correctly.

what is the actual code?

are the cooling fan(s) working?

I’ll look it up again. It didn’t mention the fan. Just that there is a problem with the coolant system

Weirdest thing my oil light came on flashing and then went off. I added oil and now the ac is running cooler then it ever has. It still isn’t cold but it’s bearable now

When the computer detects a cooling system problem it will shut off the A/C compressor.

So I did just look at my compressor and it is not spinning when I turn the ac on. How can I jump it to check it? All the fuses are good.

Does your car still have the cooling system malfunction? That must be repaired first before the engine is damaged.

I dont know much about volkswagens but I think there compressors are clutchless and have a solenoid in the compressor that is common to go bad. I think they are replaceable.

No. It turns on and shuts off every so often. But the lights been off for months

How much oil did you have to add?
How long had it been since you had checked the oil level?

What I am getting-at is the possibility that you have some serious engine issues in your near future, and that it would be a good idea to determine whether the engine is in bad condition before you spend any money on the A/C.

In other words… priorities…


I’m also curious about this low oil and oil light illumination as VDCdriver mentioned.
Depending upon a few things the A/C might become a moot point.,…

If the engine has been running chronically low on motor oil that can cause engine wear. An engine can run hotter than normal due to low compression as it simply becomes anemic.

1 Like