A/C keeps blowing the fuse???

[SlantnoseSD]

My A/C keeps blowing the fuse after I got it recharged. Its the R-12 system and it seemed to be ok before but now I got it recharged and replaced the blower motor in the front and now as soon as I turn it on it blows the fuse. I replaced the 3 fuse black and even rewired the fuses then took off the connectors tot he rotary switch and replaced those but it still blows the fuse. Any suggestions?

Could I have messed something up on installing the blower motor?

[ruf-porsche]

Blower motor could be drawing too much current. Did you test the motor before installing it?

Is the blower motor new?

[SlantnoseSD]

It is a new motor. Same as the one I took out.

[fred cook]

Check the blower motor to make certain that the fan is not jammed or binding.

[SlantnoseSD]

How can I test how much the blower motor is drawing?

[ruf-porsche]

Well you can hook up a fuse in series with the motor and see if it blow the fuse. If it blow the fuse you have a motor that is drawing too much current.

Or if you want to see how much amp it is drawing you can hookup an amp meter in series with the motor and read the amp draw.

[SlantnoseSD]

ok, I'm going to try those.

[oneblueyedog]

Check that the fuse is rated the correct amp rating. It might be too low. Mine is 20 amp.

[SlantnoseSD]

I already checked the rating. It says 25 amp but I put a 30 in and it still blew.

[Wil Ferch]

Quote.." It says 25 amp but I put a 30 in and it still blew..."

Bad logic.....use the "design value" amp rating...and chase down the "real" cause...

Otherwise you'll be tempted to use 30A....doesn't work?, well then we'll try 35A...and so it goes.....

- Wil

[SlantnoseSD]

It was only because it was all I had lying around and at that time my pop up headlights were wied to the same fuse. I have now put them on separate fuse panels.

[kuehl]

My A/C keeps blowing the fuse after I got it recharged.
"Assuming" the ac worked before and the fuse was not blowing before, and you have a few fuses handy and don't want to dive head deep, try this inexpensive (in terms of time) plug and go method:

Disconnect the compressor clutchwire, the front condenser fan plug (that is by the battery) and the evaporator fan motor plug under the smugglers box. Then, with a fresh 25 amp fuse in place, turn on the a/c system (thermostat and ac blower switch fully clockwise, set ign key in accessory position... you don't need the engine running):
A) If the fuse blows you know its something after the fuse. If the fuse does not blow then reconnect the compressor clutch wire. If the fuse blows then you then can assume it could be the clutch coil and you would check the resistance of the clutch coil (value dependent upon brand, however is usually 3 nominal ohms).
B) If the fuse does not blow after putting the clutch's load on the circuit you would then reconnect the front condenser blower motor. If the fuse blows due to the condenser blower motor then you could check the motor alone.... but on a 26 year old car if the condenser motor is original you could bet on it to be a suspect.
C) If the fuse does not blow after reconnecting the front condenser motor you would then reconnect the evaporator motor and try that. If the fuse blows due to the evaporator motor then you check the evaporator fan motor.... and so forth (you can use this quick and simple check procedure with any circuit (almost) that shares a common fuse, relay or switch.
D) You could consult the schematic at the URL below found here on PP to help you along (I wont' say it is a perfect schematic but it helps):
http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_AC.jpg

and replaced the blower motor in the front
There are three "blower motors":
(i) front condenser by the battery, for factory air cars of your era.
(ii) evaporator fan motor, under the smugglers box hatch, and
(iii) fresh air fan motor behind the dash; reach from the trunk side


Could I have messed something up on installing the blower motor?
Don't shoot yourself in the foot. Check your guns first.
PM if you need more detailed help.

[SlantnoseSD]

The fan motor that I replaced is the one in the front next to the battery.

[ruf-porsche]

That the fan motor for the front condenser. Did you upgraded the wiring to include an inline fuse? Normally PORSCHE didn't include a fuse with this motor and there have been cases of trunk fire when the motor seize and the wiring harness draw enough current to melt and start a fire.

Did someone hook this motor to a fuse in the fuse box? If they did it is wrong.

[SlantnoseSD]

It is not wired to a fuse, I just swapped the motor.

[kuehl]

Originally posted by SlantnoseSD
It is not wired to a fuse, I just swapped the motor.

Slant,
1) Try the simple procedure previously noted in this thread to check which component if any is blowing the fuse.
2) Splice in a fuse to the front condenser's fan motor as Ruf'r suggested.
3) Then go back and read the posts to your previous post
from last month:
Why does my A/C keep blowing a fuse?

[Wil Ferch]

see what I say here for parts numbers, etc...for add'l factory wiring harness that uses a 7.5A fuse for the front condenser motor....

Front Condenser Fan Fuse

- Wil

EDIT--- since no one will likely open up the link because it's too much work...here's what it says..

Part number is 911.612.077.00
Correct....part comes with fuse installed from Porsche... 7.5A fuse.
Also shown in Technical Bulletin book "E", number 8803, part identifier 8753, Group 8. ...August 12, 1988.

While you're at it, replace the A/C relay in the smugglers boot from 911.615.103.00 to 911.615.103.01

[ruf-porsche]

Originally posted by SlantnoseSD
It is not wired to a fuse, I just swapped the motor.

If its not wired to a fuse, then which fuse is blowing?

[jlb911c]

I had the same problem after replacing the motor in the smugglers box with a new Bosch. I had to replace the wires from the connection to the blower motor in the smugglers box. Once the motors starts failing the resistance cooks the wires and results in blown fuses.

Hope this helps.

[oneblueyedog]

It may be that you have an overcharge situation. I can't recall since it's been 2 years since I topped off but I think with my Seiko Sekki it's only 2 pounds r-12 max.