A/C Blower and heater Blower-same fuse??

[Booney1golf]

This is for an 85 Porsche 911 3.2

The question I have for you all is regarding the fuse that is operates my A/C blower and also the Heater blower.

The fuse in question is the 2nd fuse in the row of fuses, if you start counting from the firewall.

If I replace the fuse then I can turn on the A/C blower or the heater, either one as long as they are not at the same time. I can run the A/C blower as long as I want and as long as I turn it off first then I can pull the heater levers up and turn the heater blower to 3 and everything works fine.

However should I run the heater for a while then turn the heater off and then try and turn the A/C blower on the 2nd fuse (location described above) blows then neither the Heater blower or A/C blower will come on again until I replace this fuse.

I really did not know or think that both blower systems (A/C & Heater) would operate on the same fuse.

Also to let you know the A/C compressor has been removed and I only have been using the A/C blower to move air thru the vents to cool a little.

All other lights, components on the car are working. The car has had a new alternator put on the car about 6 months ago. The engine compartment Heater blower motor was just replaced so I just now noticed this. The A/C blower never blew the fuse until after I started having the heater blowers full operational.

Sorry for all of the info but I need some help and I was just trying to tell you all everything this feeble mind knows about whats happening.

Thanks & best regards,

Daniel Womack
Booney1golf
85 Porsche 911 Carrera Targa - And I thought Golf was addicting

[aj88cab]

Daniel

Oddly enough there are two systems that appear to run off of this fuse. The A/C system fans which includes the evaporator blower and the condenser blower. And the footwell blowers (but not the engine blower).

Are your footwell blowers working? If they are not coming on, they might be the source of the overload. Try disconnecting one foot well blower then the other and see what happens. I don't think the footwell blowers are fused in your car so you should figure out the problem before something bad happens. Then add the fuses.

The condenser blower is pretty common failure at this age of car too but it might not even be operational since you do not have the rest of the A/C installed. The condenser blower runs thru relay #6 pull it out and see what happens.

The new engine comparment blower has nothing directly to do with the circuit that is blowing fuses other than being requied to run the footwell blowers that are on the circuit. Since the footwell blowers are the new variable on the problem fuse, I would start there.

A lot of options, no definite solutions.....sorry!

Good luck
Andrew

[Booney1golf]

Thanks for your response Andrew. I will try your various suggestions even though I am not much of the mechanic type, which I know is not a good thing when you own an older 911.

The really strange part to me is that I have some fuses that are for example high beam headlight only yet for this fuse it has something to do with the A/C and heater both.

Also the fact that if I run either system while I am using the vehicle and do not use the other system until I use the car again then the fuse does not blow.

It's obviously more than my mind can understand. If I can't figure it out, after trying your suggestions then I may just have to use either the A/C blower or the heater but not use both during the same drive or day.

With the weather we have been having in the Houston area it can be on the border line on which one you need and since the A/C compressor is not connected and I just use the A/C blower fan it can be comfortable to use both (at different times) while I am out and about.

It would be nice to fix it though as I don't like things not to work properly and also I just bought an A/C compressor and I plan on getting the A/C going before the dreaded April thru September we have in Houston.

I am very grateful for this forum and your time in helping me to drive the car of my dreams at the same price or less than many cars that are on the road that don't compare to the fun and experience we all enjoy owning a Porsche 911!!!

Thanks again and best regards,
Daniel Womack - Booney1golf
85 Porsche 911 Carrera Targa - And I thought golf was addicting!!

[aj88cab]

Daniel

Start with these checks:

1. Turn on the heater system alone and make sure the engine blower and both the footwell blowers are working. Make sure the footwell blowers work at all speeds on the dial.

2. Turn off the heater system and turn on the A/C system and make sure the evaporator and the condensor fan are both working.

If you find any of the fans not working, disconnect the individual fan that is not working. The footwell blowers each have a connector behind the kick plates in the foot wells. The condenser fan has a relay (#6) on the front relay panel or a connector at the fan housing. The evaporator can be disconnected under the smugglers box. After you disconnect any bad fans try running both systems and see if the fuse blows. If it doesn't blow there is a fair chance the non running fan is the cause.

If all the fans are working then you could have a short or one of the fans is nearing end of life and drawing too much current. Do any of the fans squeek when they start or run? Disconnect each fan one at a time and run the remaining fans of both systems to see if one of the fans is causing the problem.

Try these and let us know what happens.