More A/C related goodness...

[Scottn59c]

Some of you may have read the ongoing saga of problems I've been having since installing a new AC compressor.

Got the van back from the mechanic today, who explained that (now that he has charged the A/C system), the radiator fans are not working properly when the van is parked, but they work once I drive and air flows through the compressor.

If I try to run the A/C while parked, the engine cuts out and the battery/alternator light comes on. Any idea why?

Saw a thread describing similar symptoms suggesting that the culprit might be the radiator fan resistors, which can get corroded. Does that strike you as plausible?

http://forums.vwvortex.com/showthread.php?5359155-...s-on-HELP!
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Farfignewton!

[Abscate]

The fans should kick on as soon as the AC compressor comes on, commanded by the ECu. No fans could explain high system pressure
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.ssS!

[Scottn59c]

Right - the lack of fans is definitely what is causing the high system pressure - the most recent mechanic said as much. So the question is, why aren't the fans working when the van is not moving?

I can look into the fan resistors, but curiously, I didn't have this problem when the first (aftermarket) compressor was installed a month ago. My intuition tells me something wasn't done right during the second installation.
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Farfignewton!

[Stripped66]

First, check the connections on the fan resistors, and the fuse to the after-run coolant pump (fuse 19? 10 amp).

It would seem odd for both of the fan resistors to fail, if they are not simply disconnected. If the low or intermediate fan speeds are not coming on as engine temp increases, it could be that the fuse to the after-run coolant pump has blown, as this circuit provides the (+) feed to the fan circuit within the A/C relay and the Fan Control Thermal Switch. The fans could still switch to high-speed through the 3rd-speed Fan Control Thermal Switch. If the fans only come on at intermediate or high speed, then it's possible that the low-speed circuit within the Coolant Fan Control Relay is bad.

If the low fan speed does come on as the engine coolant temp increases, then the Coolant Fan Control Relay and resistors are working fine, and the after-run coolant pump fuse should also be fine. Investigate the black/red wire from the Coolant Fan Control Relay back to the A/C relay. This black/red wire is energized by the A/C relay simultaneously when the A/C clutch is activated. You know the A/C clutch is working, so the black/red wire should be sending (+) to the Coolant Fan Control Relay.
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[Scottn59c]

Stripped66,

Good advice, and I'm planning to do some fuse and continuity checks tonight when I get home tonight. I'm going to check those fan resistors, but you're right - unless they're unplugged, it doesn't make sense that they'd work before installation and then not afterwards. I'll check out the relays and see what I find.

What are the odds that the compressor itself is the problem? I mean, the aftermarket one installed last week worked perfectly, but didn't fit right and created the belt chirp. No fan problems then. Now with this new OEM one, all of a sudden I've got the fan problems. The mechanic did note that the OEM compressor arrived without any oil in it (he subsequently filled it). Hmmm...is something screwy going on with the wiring, or is this compressor defective?
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Farfignewton!

[Stripped66]

[Scottn59c]

Did some more experiments today. Here's what I found:

Tried driving around and playing with the AC settings. Things seemed okay during the road test and as engine was warming up.

When I put the van into idle in my driveway and cranked the AC, it caused the van to stall and the battery/alternator light to come on. Repeated this a few times with the same results - stalling after roughly one minute. The radiator fans are NOT moving while the van is idle. Engine bay is scalding hot, though no overheating yet.

All fuses checked out okay. The radiator fan resistors are hooked up, but look pretty toasted - rubber coating is worn away and the coils are exposed and dirty looking. But then again, why would they both suddenly fail together now? Doesn't make sense.

What else could cause those radiator fans to stop moving? Next I need to look at the relays. 2nd shop said bad fan module relay could be a possibility. But dangit, I can't get over the fact that the fans worked okay with the last compressor one week ago but not with the new one. I really wonder if this compressor is defective. First shop was adamant that they thought it was, but first shop didn't gain my confidence during the process of this long fiasco...
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Farfignewton!

[Stripped66]

Check all connections with temp sensors, including the temp sensor on the passenger-side radiator end-tank, and the temp sensors on the coolant manifold. Locate the fan control relay, make sure its connected and the wiring to and from the relay are not damaged. Check the strip fuses that are in front of the battery...these are the fuses for the cooling fans.


If you cannot find a simple fix with the wiring or strip fuses, take the van to the dealership, pay the piper and let somebody who is qualified diagnose and repair the problem.


BTW, you have a vacuum leak. That's the reason why your vents don't work properly at idle, but do when you're driving; and it may also why your engine dies after a short time when idling with the A/C on. The explanation provided by the mechanic ("...but they work once I drive and air flows through the compressor") -if that's what he said verbatim- also indicates that he is a moron and doesn't know what the bloody hell he's talking about. Holy crap.

Take it to the dealership before you contemplate insurance fraud or go bankrupt.
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[Scottn59c]

Guys, thanks so much for your help so far. Still troubleshooting. I'm a novice, so your help and ideas are all I've got, short of emptying the wallet, which I've already done without much effect.

I pulled off one of the radiator fan resistors for closer inspection. In the pictures here, you can see that it looks pretty toasted with some breaks in the coils. I can't tell, but it looks like wires (white) alternate with rubber, (black) or both colors could be wires. I see splits in the blacks, not the whites, though.

I attempted to test for continuity, but again, I'm an amateur, so I'm not sure what to make of it. I got continuity on two of the terminals, but not on the third (see pics).

Can you tell enough from this info to let me know if you think the resistor is okay or if it looks like it might be my culprit? Looks like new ones are $50 each. Still can't imagine why they would have quit working together, in tandem, a week after they seemed to be working with the earlier compressor...

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Farfignewton!

[Stripped66]

You should have continuity through all 3 combinations of terminal pairings. I'm just guessing that the outer terminal in the photo that shows no continuity is the output to the fan (if the plug body shows a number alongside each lead, #3 would be the output to the fan), which would explain why your fans are not running on low or intermediate speed, either with the A/C on or as the engine warms up. (the fans will still run on high-speed if the engine temp exceeds 226F).

Don't ever underestimate Murphy to kick you when you're down. Replace.

[Scottn59c]

[Stripped66]

[Scottn59c]

[Stripped66]

[Scottn59c]

Hell yeah! Ordered a new fan resistor, it arrived, and we've now got action from the left fan. Only ordered one because I wasn't sure if this was my problem. Will order the second one today. Hey J., thanks for your help, man! You were right - the new one has continuity in all three terminals. Abscate, thanks to you too!
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Farfignewton!

[Abscate]

Well done ,Scott!

Can you swap it into the other two positions to see if it works the others?

More than likely someone banged them when doing your compressor, but they looked pretty shot to be fair
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.ssS!

[djkeev]