I have a 1988 E150 whose climate control fan output appears to be stuck on "floor" regardless of where the dash slider is positioned. The temperature blending for heat and the heater core itself both appear to work right, but there is also a problem with the factory AC (compressor not kicking in).

What controls the output of the air between windshield, dash, and floor? Vacuum? Cable? Is the non-functioning AC compressor related or should I be able to troubleshoot them separately?

Thanks
Dan

 

Digging up the past here, but wondering if you ever figured it out? I have an '88 F-150 with the same problem, but mine is stuck on defrost no matter where the slider is positioned.

 

Your '88 would be vacuum controlled, check your vacuum lines running to the heater box, vacuum reserve, and even inside the heater box, the slider switch in turns sends a pulse to a servo motor, that opens and closes the blend door inside the heater box, blowing on defrost only is a sign of a vacuum problem.

 

Hi Jeremy,
it may not help much but here was the problem with my '88 blowing only panel air (A/C) vents. I think the default with no vacuum applied is defrost. There is a 2nd actuator that selects floor or defrost or both (called Mix).

https://picasaweb.google.com/jimandn...HeaterAirflow#

If you shut off the engine and move the controls, you should hear the actuators moving as the vacuum switches. The vacuum tank is next to the brake master cylinder.
jim

 

Jim those are extremely helpful and informative photos for that series of E-Vans----thanks for documenting your fix.

Sent you a PM about this.............

 

I know I am late to this party but need some similar help and the photos referenced are no longer available. My '88 E250 it blowing air, just none of it is warm. Any help is appreciated.

 

I have no clue about a van as old as your's however this link might be helpful: E-Series Vacuum Controls

If it doesn't help I'd be of no help what so ever. Good luck!

 

thank you.

 

Is the selector control working as in the air comes out the vents that the selector control is set to? They work between floor, vent, and defrost?

 

Yes, it goes the direction of the selector, it just doesn't get warm. The engine does come up to temp.

 

There could be a couple of issues. You need to check the heater hoses and see if both in and out are getting hot. Some vans use a heater control valve that closes off the water flow to the heater core when the heat is off. My 1988 E150 with a single front heater does not have one. I do not know about yours. But if you put your hand on goth heater hoses, under the hood, going into the heater core, both should be hot..
Here is what the valve would look like and may be used to control the flow to the rear heater if you have one..




Another thing to check is to feel of the heater case on the inside. The heater core is installed on the left side of the case in the passenger side foot well area. with the engine up to temperature, that area of the heater case should be at least a little warm to the touch.

There is a vent door that opens and closes between the heater core and the AC evaporator and is controlled by the temperature slide control. "evaporator temperature control door" It uses a cable to open and close the door. There could be something broken or the cable came loose to the door and it is stuck in the cool position not allowing air flow over the heater core.

Maybe this will help.


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Thank you so much, you've given me some 'hope'. I will try to go over to my garage today and report back with my findings.

 

Drove it around and brought it up to temp. No evidence of warmth in either hose. This is probably going beyond my level of competence and I will look for a professional shop to take the lead. Thank you for your help

 

Good luck and please follow up and let us know what they find and repair so the thread wont be left hanging unresolved.

BTW do you have a factory rear heater? If so your heater control panel will have 2 separate fan switches. If you were checking the correct heater hoses and both were cold, then you have no flow through the heater core. If the heater core is clogged up then I recommend replacing it as well as flushing your cooling system. The front heater core is really easy to replace. I did mine last summer and it took me about 2 hrs.

Also the diagram below is or a single front heater and a 5.0 engine. The 5.0, 5.8, and 7.5 heater hoses all connect a bit different at the engine but are all the same where the hoses connect to the front heater core. I marked those 2 hoses in yellow and a H in a yellow circle. So no matter which engine you have or if you have a front and rear heater or just front, if you feel of the lines where they go into the front heater core, they should be hot..

 

Amazing help, much appreciated. It goes in Wednesday at 8am and I will follow up on the site thereafter.