Heater control valve

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Dec 10, 2010 | 12:46 PM

66 F-100

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Heater control valve

Hi Guys! OK, I have a 96 E150 conversion van, and the heat barely works. Plenty of air, just not very warm. I checked the thermostat, and it's fine. I replaced it with a new 195 degree unit, and no change. I think it's probably the control valve not opening far enough to let enough coolant through the valve. The problem is, I can't find the valve. I bought the Chilton book, hoping it would be better than their other books, but of course it's of no help. It only talks about a cable control, and mine is vacuum controlled. Can someone tell me where the valve is? The book talks about removing the glove box cover, but this van doesn't have a glove box.
Thanks!!

Dec 10, 2010 | 02:14 PM

66 F-100

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Update...it doesn't have a valve. It's done more like my 66, where the coolant is always running thru the heater core, the heat control just controls how much of the air is moved thru the heater core. Everything appears to be working properly, the door goes all the way in either direction, depending on where I put the temp control. I guess my next step is to check for proper flow thru the heater core? The van only has 60k on it, so I wouldn't think anything should be clogged up, but I guess it could be. I have an infrared thermometer, so I guess I'll check the surface temp of the heater core, vs the coolant lines leading to/away from it.

Dec 10, 2010 | 04:02 PM

Henry10s

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Does it have rear core / heat?

Dec 11, 2010 | 02:45 PM

66 F-100

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Yes, and it's even colder than the front one. The hottest temp I could find anywhere was 186, at the output of the T-stat housing, leading to the top radiator hose. That's with a 195 degree T-stat. The hottest I could find on the heater lines was 134, directly off the water pump. By the time it got to the "T", where the line splits to go to the front and back (only about 2 feet of line between the T and the pump), it was only 107, and the hottest I read on the front heater core was 102. I haven't got the back one exposed yet, but I figure it would be very cool. The lines leading to it are 89 degrees, at the place that is as close to the rear core as I can get to. It's like there isn't enough water being sent through the lines, to get them hot.
Anybody have any ideas?

Dec 11, 2010 | 05:18 PM

Henry10s

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From: NY, NY

My 95 E-150 ran initially too cool for my liking . It just took a long time to heat up and get over the 5 o'clock / "C" line. Winter was worse. Un-insulated lines beneath the van (rear heater) also played a role. Rear heater was useless originally.

After servicing the system (back-flush, thermostat, new hoses) and insulating the rear lines I started getting some heat, and yes coolant gauge still showed a cool engine (4 o'clock), but not as cool.

Dec 12, 2010 | 12:37 PM

precisiontile

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From: Southeast Kansas

I own a 1995 E250 and was having an issue pretty close to this one. My heater worked fine but the air conditioning would go from cold to hot and back to cold randomly. I thought it was the electronic control box under the passenger side (right side of heater core), cause it was moving the blend door randomly back and forth(open and closing), regardless of where the hot/cold switch was. So I replaced it. No change! We have a parts van that had the dash apart so I took the Air/heat control unit (on the dash) loose and removed the hot/cold lever switch (which is vacuum) and installed it on my van. This solved the issue of my air randomly switching from hot and cold. I know that it might be a long shot but worth checking, the places I took my van to all had different opinions to my problem but no one had mentioned the switch in the dash. to let you know the bad unit in my van would sometimes only open or close halfway, kinda like the problem you are having. Hope this helps!

Jan 4, 2011 | 04:03 PM

66 F-100

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Well, I finally got it solved today. I had noticed that when I changed the thermostat, the antifreeze was a little dark. I figured they had mixed the old green with some of the new "mixes with any color" stuff. Upon closer inspection yesterday, I realized they had mixed old green with dexcool, or something similar, and it caused some gel-like chunks in the antifreeze. I figured this had probably clogged things up. I flushed the entire system, in both directions, refiled it, and presto, I had heat. Before the work, I was lucky to get 110 degrees from the vents. now I get almost 160!
The moral: Never, EVER, mix green and orange. I refilled with good old green antifreeze, per Ford's guidance.
Thanks to all!!

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Jan 4, 2011 | 08:45 PM

66 F-100

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Same as always, about dead center. The engine heat was never a problem, just wasn't getting to the cabin. The back one isn't working, but that's the rear heater control valve. There's a vacuum signal going to it, but it's not opening.