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condenser fan

N

Nick Green

PCGB Member
Member
Hi,
noticed in the last few days that as soon as i turn the air con on in my car the condenser fan under the front wing starts to cut in and out. It probably turns on and off every 20 seconds.
Any suggestions?
thanks
Nick
 
Nick,

Two immediate thoughts come to mind:

1) Blown fuse for rear blower - in rear electrical box in engine compartment. Should be a 30 amp fuse despite possible documentation which implies 25 amp.

2) Broken/corroded ballast resistor for condenser fan. Mounted on top of condenser - real PITA to replace.

Regards

Dave
 
Hi

Yeah mine appears to be doing the same on my 964 Turbo.

Let me know if you cure it so I know how to solve mine.

Is it an issue or can it be left?

Jeremy
 
thanks dave. I looked at the fuses last night and they seem to be ok. Is there any way of testing to see if the problem is the resistor?
thanks
 
Nick,

You can check the low speed operation of the rear blower fairly easily. Just turn the temperature knob towards red and the rear blower should start up in slow mode (with the ignition on, of course).

Testing the condenser ballast resistor is a bit more tricky. It's worth doing a swap of the relays (the condenser, oil cooler and rear blower all use identical relays which can be swapped around to prove a point). However, the most common cause of the cycling condenser fan is, as I said before, a corroded ballast resistor. The only real way to check it is to remove the nearside front wheel arch liner and take the thing out. It's attached to the top of the condenser (a ceramic disc about an inch and a bit in diameter). Unfortunately there is a battery vent pipe close to where it's mounted and it does it's best to corrode the ceramic.

Regards

Dave
 
yes replaced mine last year after your help, managed in a badly lit garage working mostly by feel, much easier when i found out the round resistor is attatched by an allen head not the 8mm spanner i was trying to use doh!
handy article and photos on rennlist diy site too

D0B66ED2EDFE4C46B50B14A70678E7BB.jpg
 
Changed the ballast resistor at the weekend and problem solved. The old resistor was falling apart!!

Very difficult to get to though - needed a mirror on a pair of forceps to see how it was attachde to the condensor!!

All done now so thanks for all the advice.

Jeremy [:D]
 
hi Dave
just been in garage and you are correct as the resistor had crumbled to pieces. You are also more than correct about it being a PITA to get at!!
Unfortunately the retaining screw absolutely refuses to budge so I think I will have to secure some other way.
The other thing is that with the new resistor fitted, the fan runs continuously at half speed when the air con is turned on.Is this right? Iam sure it didn't previously.
cheers
Nick
 
Nick,

I'm pretty sure it's right that it does run at slow speed all the time the a/c is on. The fan is usually pretty quiet at slow speed so it's difficult to tell but TTBoMK it's right.

Regards

Dave
 
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