heater problem?

[Commish56]

I have a 93 ATX with 126k on it. I have had the 60k and trany rebuilt within the last 2500 miles.Got into my car this morning and turned on heat. It is blowing on and off. when it does come on it is at full blast. also i hear a clicking noise in the dash while it is doing this. Heat does come out hot and when i try to lower the blower manualy it does nothing. I have read some posts with some of this problems, but different remedies. Some say bad ground and blend door accuator. Want some input on it. thank you in advance!!

 

[rubydist]

So the fan runs only full blast? Or the temp is only full hot?

The temp full hot and the clicking under the dash suggest a blend door / blend door actuator problem.

The fan running only full blast suggests a bad blower control unit.

 

[sperold]

Exactly like above, (Rubydist).
If it is still clicking, I think the blend door actuator can be saved if you can get to it. The pivot that the door swings around can get hung up. The clicking is the actuator trying to swing the door to the proper location to deliver the air at the temperature you have dialed-in on your dash unit. The system also takes over the fan (when things are right) and has the fan on a high speed to deliver the most air at this dialed-in temperature. As the interior warms up, the fan adjusts itself to pump our less air until finally it is putting out next to nothing. If you interfere and manually hit the fan scroll, it overrides this feature.
You can still buy the blend door actuator new at Shosource if it is too late, but try to save the one you have. If possible, turn it off until you can get to it.

 

[Commish56]

The fan runs at full blast. I have not left the heat on long enough to see If it is only hot. Is there a way I can check the blower control unit. I have also read some posts that it could be a bad #17 fuse. Is there anyway to check on or get to blend door without ripping dash apart. Thank you for the replies

 

[Commish56]

Also it is not showing any codes.

 

[sperold]

I have seen on the internet (google blend door) that on an Explorer, someone dremmeled his way to the blend door and repaired the hinge with a small sleeve.
I have seen no such posts for the SHO, and you would need help on that because many things are in the same area.
If I am not mistaken, not only must the dash be lifted up (or out) but the "box" has to come out, which means messing with the heater core and those hoses on the firewall. Also the AC has to be uncoupled, so it is a difficult procedure.
Get more advice, and ask if anyone has dremmeled a SHO.
The default on the system must be blend door open to heated air and the fan on high, because that is how they all behave when pooched.

 

[bully06]

The running on full blast sounds like a blower motor resistor, when they go you will only have the high mode on blower control.

 

[Commish56]

I just checked on it again. Now it is not clicking on and off. It is doing it very periodically now. When it does do it. It seems that it is shutting the heating system down then restarting. Also it only comes on at full blast even if I turn fan to low manually. Is there a way for the pivot that the door swings around to just get unstuck. I am hoping that it will somehow fix itself but I highly doubt it. Can unhookin battery help. She is running great with no problems for a while now. Hoping that it's an easy fix as taking apart dash does not seem easy. Thank you for input

 

[Guido0136]

I just checked on it again. Now it is not clicking on and off. It is doing it very periodically now. When it does do it. It seems that it is shutting the heating system down then restarting. Also it only comes on at full blast even if I turn fan to low manually. Is there a way for the pivot that the door swings around to just get unstuck. I am hoping that it will somehow fix itself but I highly doubt it. Can unhookin battery help. She is running great with no problems for a while now. Hoping that it's an easy fix as taking apart dash does not seem easy. Thank you for input

If the fan is blowing on high and no matter what you do is will stays on high, then check the BCM (Blower Control Module) it's also known as the Blower Control resister. It's behind/below the glove box and is an easy fix.

Search the forums for BCM or blower control module and you'll get several hits, including one that I posted in as I had this same issue.

New ones are hard if not impossible to come by so look in the classified sections. I might have access to one soon (from a 95 ATX parts car) if you have an issues finding one.

Hope this helps.

 

[Commish56]

Great help. I am leaning toward this myself. Is there a way I can test the bcm. I have read some posts on the bcm. But could not find one on how to test it. If there is a way. I am def interested in part as I have read new it is around 200. Also is the eatc in good condition. My buttons are cracked.

 

[Guido0136]

Well my EATC is also cracked but the hard button from the 95 parts cars is mine.

It's in the trunk right now and just need a warmer day to install it. Check the classified section and wait for other members to chime up. Someone might have one for yah.

Good Luck.

 

[fz1nsho]

mine did the same until the other day when the clicking quit and the blower didnt shut off no even with the controls turned off. very annoying. 70 degrees out windows down blower on full blast blowing heat. I found out today that the problem is the blower motor resistor. theres a "snap disc" on it. thats whats making the "clicking sound" Its very expensive to fix. 219 at autozone. Im not happy about it. Im hoping it fixes another problem im having. When ever the heat or a/c is on my car surges. best way to explain it is say im going a steady speed of 30 mph, the car will surge with power. my speed and rpm stays the same but i can feel a little power surge over and over until it turn the heat off. It really ****** me off. lol