My uncle gave me 88 E150 a couple of months ago and it had been sitting under a tree. He said that I would have to clean out the blower fan, because leaves always got in there and blocked air flow. Well, anyway I just took it it apart and cleaned out handfuls of leaves and the front vents blow out warm, but not as hard it should and the back vents blow hard but are not HOT. It has factory A/C. Please help me figure out what is wrong. I am going to take out the heater core and make sure that all of the debri is clear from it, but I still don't see how it would affect the rear heat.

 

i have a 79 e150 with rear heat-when i got it someone had hooked the hoses together underneath so no water was going through the rear heater core,-just something to check,also there is a valve in the line that shuts off the water for a/c use maybe it is stuck closed

 

Howdy,
Where abouts is the rear valve? My '87 blows decent heat from the defrost, but freezes my kids out with barely tepid air. I end up wearing a long sleeve shirt with two boys in coats and hats.
Also, how's the best way to hook up the cable to the temp. reg. door in the heat assembly? Mine got unhooked at some point. It'll be no big deal until spring at this point.
-John R.

 

The rear heater control valve is in the heater hose going to the rear heater core on the driver's side under the engine cover. You should be able to see it from underneath the van. If not, pull the engine cover. Might be a good idea to disconnect those hoses and flush that rear core both ways. Is the thermostat OK?

 

Howdy,
It's a good thermostat. When I got the thing, the vacuume lines had problems. I'll check out that area as well now.
Thanks!
-John R.

 

Ok, I have seen the valve with the vacuum line on it. My question is what makes the valve open (switch, etc.)? Can anybody send me a vacuum diagram or tell me where the vaccum hose goes to that comes from the valve?

 

Think it goes to the A/C-Heat control switch. If you watch the valve while switching between A/C and Heat, you should be able to see if it's working.

 

I think that I have a vacuum leak, because it blows hot when I stay at a constant speed like the highway, but if I'm around town it doesn't blow hot. So, I think that the vacuum bleeds of when I let off the gas which shuts the valve off to the rear heater core. The front heat stays warm, It's just the rear that cuts in and out. I was thinking of installing a manual valve and leaving it open during winter and closing it during summer.

 

If you verified that the valve is working, I'm thinking that maybe the rear core needs flushing and you're just not getting enough flow through it at lower engine speeds. I guess if you lock the valve open and get the same symptoms, that's what it is...
Anyway, let us know what happens and good luck.