MassGuy

OK. Here is the first problem I need to zap on the 1991 Cab C4 I just purchased and yes she is home!

The battery is new. The heat blower is not functioning. Upon start up it goes on for maybe 2 seconds and the nothing.

When everything is off and all is quiet I believe I can hear a very quiet fan?...this is after a 1 hour drive....maybe some kind of cooling fan?....It sounds like its coming from behind the dash though?

I would be eternally grateful if we could figure this out. This car is so nice otherwise!!!

Thanks in advance for your help......

1990-964

Hi,
I am not sure about your blower issue, but the fan you hear is probably the climate control fan on the rear of the unit. I can hear this fan in my car also and asked the shop about it. They told me that it blows air across the temp sensor to give the sensor a better reading of cabin temp for the auto function. The system will work work if this little fan is not running. If you are worried about it running while the car is shut off you can remove the control unit ( fashion a couple of u shaped removal tools out of old coat hangar to fit into the holes on the outboard sides on the face of the unit and push the box out from behind) and unplug the fan. I ran mine this way for a couple of years then re-connected it and don't really notice a difference. So it's your call. Take some comfot and try not to stress too much because the climate control in the 964 is s**t compared to almost any other car. Good luck.

Darren

JasonAndreas

Most likely the rear blower motor or ballast resistor has failed or tripped a themoswitch. You could try resetting it (see image below). As a temporary (get you through the week) fix I think you can disconnect the rear blower motor and the front fans will operate at speed 1 which will at least make the car driveable in the cold weather we are having. Where in Mass are you located?



The CCU cabin temperature sensor fan should operate for 20 minutes after you turn off the ignition. If it doesn't shutoff after 20 minutes it will drain your battery in about 2 days time.

MassGuy

I am in Methuen. Thank you for responding and I will look into your suggestions.



The fan I heard did shut off when I went back to check. This was also in about 20 minutes time just as you said.

How can I reset this resisitor?

Where are these pieces located? I would l ike to look into this tomorrow.

What would be the permanent fix?

Thanks!

Eric Kessel

MassGuy,
Have you checked the fuse for the rear blower motor (it's in the rear fuse box). If the rear blower motor is bad/fuse blown, you can't run the front blowers when the temperature **** is not on the blue dot setting (full cold). Set the temperature setting to the blue dot, and see if the blowers start working. I'm down in Andover if you want help going through this sometime.

MassGuy

Eric very cool of you to offer. If I cannot get it done I may need some help. I am commited to DIY. I refuse to lay out $100 hr at the dealership.

Eric Kessel

Dealership? Hahahahahah that's funny! There aren't too many around here that bother with cars this old......... If you have a laptop running windows, I can give you a homebuilt board to run
Doug's scantool software to try (just don't laugh at the board). The climate control does give error codes....... Let me know.
-Eric

MassGuy

For sure lets me up some time. I will keep in touch. After the holiday if the weather stays decent I am going to scope this out better. Right now I am butied in holiday festivities!

One question though.....Where is the rear fuse box?

I am sure after a few months I will have a better feel but for now I need all the help I can get......

Thanks!

Marc Shaw

The rear fuse box is the vaguely triangular shaped flat box attached to the left side of the engine compartment.

The pieces that Jason showed are in the rear blower tube that is the approx. 3" wide black pipe that runs down the rear left of the engine compartment. The temp. sensor (pointy part) is in the top centre while the resistor part is tucked down the extreme left side by the rear fuse box - just be very careful - that resistor gets hot enough to burn you or start a fire so be sure you have re-installed it correctly and securely.

Marc

MassGuy

I did locate the temperature sensor and resistor. The resistor was hanging out of the tube and the temp. sensor was very loose. I think the dealer guy was trying to figure this out himself before I took ownership or they wiggled loose??

I located the fuse box and I found that the 30 amp fuse was blown......Does this mean anything with regards to the other components?

It is functioning now......

I get concerned with blown fuses as they are usually a symptom and not the cause. I dont have time for a complete test drive as we prepare for our New Years celebration. I will try to sneak in a quick one.........

Anything else I should look for or does it appear to be fixed?

I cannot thank you guys enough for this kind of help it is much apreciated!!!!

Eric Kessel

The fuse blows when the motor is going bad........... If it works, don't worry about it. Next time it blows, it might be time to start looking for a new motor. Vertex used to sell just the motor for about $100, but they haven't listed it for a while (year or so). Used off e-bay is a waste, since the assembly will probably be worse than what you've already got (I bought two off e-bay before giving up).

MassGuy

Ok so I will keep my fingers crossed and again thanks for all the help!

wf758

Eric, what is Doug's scantool software? Is this something whereby we can read error codes? If so, how do you interface your computer with the car?

Thanks...and Happy New Year.

Eric Kessel

W (Franklin),
Doug B wrote a nice little windows application which allows reading and clearing fault codes on OBD I cars (964 and 993's). You need to build a little signal interface board (RS-232 -> OBD I specs), which is maybe $20 in parts. If you take a look at the following links you can get a good idea.

https://rennlist.com/forums/showthre...light=scantool

https://rennlist.com/forums/showthre...light=scantool

https://rennlist.com/forums/showthre...light=scantool

Previously you had to go to the dealer to get airbag faults reset, but could use the accelerator pedal to get blink codes from the check engine light (CEL).

ABQ Slim

I just replaced the blower motor in my '90 Cab (after making horrible noises and blowing the fuse). I got the motor from Autohaus AZ (no affil.) for $398.95, including shipping.

http://www.autohausaz.com/

My dealer wanted $940, and wouldn't give me a quote for the whole job without bringing the car in. I'll post a DIY with pictures in a couple days.

Tony