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Aircon/Heater problem!

danmason

danmason

New member
Discovered last night that the aircon / heater fuse in my 944t had blown, so replaced it today with an identical 7.5A fuse. 5 mins later, it had blown again! Now, I tried out the Demist function, also the aircon (which currently needs charging) ; I don' t know at which point the fuse went because I only tried them for a couple of seconds each. Could I have blown the fuse just by messing around like this, or am I looking at an electrical problem that going to be horrendous to resolve? Can anyone offer me advice before I try the other spare fuse?

Thanks
Dan
 
First thing to do would be to replace the fuse with an ammeter, so you will at least know if it is taking more than 7.5 amps.
If so, then you do have a problem - may not be expensive, just time consuming.
If not, then it would seem that the fuses are the problem.

Not too much help, but it is a start.
 
I don' t have my list of fuses in front of me but IIRC (if I remember correctly) there are a number of items on that same fuse.

I know this because mine kept blowing when I first had my car. I traced it to the heated rear window. There are two tiny wires from the tailgate struts to the car, these get very brittle and corroded. New wires and bayonet clips stopped the problem.

Not saying yours is the same but worth a look.
 
I had the same problem too, except my bayonet fitting snapped off when I tried to clean the connectors! A new one sorted out the blown fuses.
 
Hi guys, thanks for the advice so far. I will try the rear window heater thing tonight (was too busy on the 924 at the weekend!). In case the bayonet fitting / wires are beyond repair, any idea where I can obtain replacements?

One thing I was able to ascertain at the weekend is that there is WAY more than 7.5A going through there. I couldn' t get an ammeter in there properly, so decided I could take a measurement across the two terminals of a fuse. I duly put in a higher rated fuse that I figured wouldn' t blow (20A) and.... you guessed it, it blew within about 5 secs of switching on the aircon.

This seems a ridiculously high current - should I be worried? [:eek:]
 
I have heard that the a/c has an electrostatic clutch on the compressor - I have heard people before talking about it failing - hasn' t happened to me so can' t give you anymore details but if the fuse is blowing when the a/c is switched on i would look there. Also switching on the A/C starts the second radiator fan this could also be worth investigating.
Good luck,
keep us informed,
Tony
 
UPDATE! Firstly, the rear window stuff checked out fine - all the wires are mint. I also found that the rear window heater is not affected by the problem - it works fine, and seems to be on a different fuse.

So, I guess it' s time to take a look at the compressor :rolleyes:
 
Following further investigation, it SEEMS the problem only occurs when the engine is warm. If I turn the aircon on when the engine is cold - it runs faultlessly. But it seems that once the engine warms up, turning on the aircon doesn' t work because the fuse is blowing! I say ' it seems' because I' m unclear how this problem could occur. Could it relate to the main radiator fan? The aircon fan is functioning normally. Or is the compressor overheating? I' m getting confused...[8|]
 
Amateur mechanic time [8D]

To rule out the main radiator fan somehow interfering with the fuse why not start the car from cold. Switch on the A/C and watch the second fan switch on automatically. Wait for the car to warm up and if your fuse blows when the main fan switches in then you at least know what it is.
 
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