ac related aux fan

[fstenb]

Hi all,

I need an answer if a failed aux fan inhibits funtionality of AC or just decrease efficiency of the cooling. If at standstill i can understand. But when driving it should work with a bit of loss maybe. Cold here so i can't verify this. 2-3 deg outside.
I can hear the clutch engage when switching to cold "blue".

Regards

[tendril]

Decreased efficiency only.

[BobieM]

A/C will continue to work, the efficiency of the cooling is decreased, as the auxiliary fan isn't there to push additional air into the engine compartment.


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[Timm]

If the fan failed in the normal way (it seizes up and blows Fuse 25) - then your idle will be lower than usual when the compressor kicks in!

[ltbrett]

Depends on how you use your a/c with no aux fan. If you run the a/c in a situation when the aux fan would normally run (like while idling when hot outside), system pressure will increase dramatically. The compressor will probably cycle on and off because of overpressure. The clutch won't be too happy engaging with system pressure that high either. So yes, the a/c will work without an aux fan, but you risk damaging your compressor and clutch. As an aside, if you find your a/c cools very well for 10-15 minutes then cycles on and off, you probably either have low charge or a condenser problem like a faulty aux fan or obstructed air flow.

Brett

[fstenb]

Timm, i have studied your excellent description and sorry to say that fuse 25 is in perfect condition. Aux fan is shot and ready as a wall hanger (confirmed now). Just one thing after another before the sale of my car. I think the AC is working fine and this is important. Tomorrow i will have an AC leak test and new 134 before the sale.
regards

[Timm]

Yes, that's a good point - as that is exactly what mine did when my aux fan fizzled out. I got the A/C regassed, the A/C was lovely and cold for about 5 minutes and then it gave up and the cabin warmed up - a few minutes later it fired up again and cooled the cabin, As the compressor was not cutting in after a few minutes I worked out this was due to over-pressure - and that's when I found the fan had failed.

So, from experience, without the aux fan the refrigerant pressure rises enough to disable to compressor (via the high-pressure switch).

[ltbrett]

fstenb, there is nothing to gain by performing a leak test or from getting new 134a. If the system has refrigerant in it, there is no leak, aside from normal slow loss through hose walls. Refrigerant does not wear out, so no need to replace it. You can replace it for the purpose of weighing in an exact charge, but a competent technician can achieve the same result with pressure gauges and a thermometer. Just trying to save you some krona.

Brett

[fstenb]

Brett, it's more 15 years ago i had it checked. I't was working fine until 2 years ago when i garaged the car. Probably when the AUX fan went bad. It's only for the safety of the buyer. I started working on the car last Nov and found a number of problems, now most fixed with OEM parts.

// Freddy

[fstenb]

Timm, this is a good lesson for us. Got the car back from AC service. Low on 134a. Now cold as he.... Sorry to say that it is going on Friday. End of 15 years of joy and 10 years of membership in this excellent forum. Hats of to all of you. By the way they now use a tracer that don't need UV.

Here's the data for my car:
new gas : 1.450 kg
tracer : 7 ml
gas retrieved : 0.085 kg
vacum test ok

Regards Freddy.