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Little heat, defroster flap not opening


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I do not know if I have to rebuild the heater box, looked at articles. There is little heat and the flaps to send heat to the defroster doesn't work.

First heat issue: after running the car with heat on put my hand on either side of the valve and it seems like both sides are warm, the return line is warm not hot. Moving the cable while having someone hold their hand on the wire on the valve it seems like the valve is opening and closing, not stuck. I was thinking the first step would be taking it out and seeing if it opens and closes.

Went to the passenger side because that was supposed to be easiest and took off the large plastic hose and put my hand in to see if the flaps would open and close. Not working real well, can open the flap manually and it wil close with the lever inside car but won't open. Forgot to run the car with the fan on to see if was blowing.

do I have to refurbish the heater box? Did n't look at the drives side flaps as it seemd harder to acfcess

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get down in there with a flash light and look &

feel with your fingers up inside the floor vent

openings while you move the control levers

Make sure things are connected to the cables

and yes - your water valve might have an internal leak,

or it's valve is not rotating fully to OPEN or CLOSED ?



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Do a little research on the heater box. You will find out there is an awful lot of things going on in there with the flaps and cables and valve and stuff.

There is a real good write up in the FAQ's about rebuilding the heater box. It's the sort of job that you only want to go in once to do, so do everything. I spent a couple of weeks of evenings working on mine. It works very well, (I still need to fine tune the valve position) and gave me a new apreciation for the whole assembly.

New bowden cables will make a world of difference in how smoothly the flaps operate. However, you will also need to replace the rubber bushings at each end of the flaps. I found some wire grommets at the local hardware store that fit well. Also, clean off the flap surface and glue on new closed cell foam. The old stuff is probably long-gone.

The control valve is the usual repair. Take time to ensure it is still mounted securely. I had to fab up a new mounting bracket for mine. While you have it all apart, take the heater core to a radiator shop to inspect/repair.

After you pull and install a heater box once, you understand not wanting to have to pull and install it again.

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test it, remove the arm from the valve, not the cable from the arm. Much easier to reinstall that way. Just make sure and note the position of the arm, and whether the heater control is set to warm or cold. It's very easy to reinstall the arm incorrectly so that when the lever is set on cold, you have warm air and vice versa. Wonder if that could be your problem now, courtesy of a PO who wasn't paying attention...



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Guest Anonymous

Before you start pulling things apart, is the heat gauge at least in the middle? You have to have hot coolant to make heat. Next, it is possible to remove the hoses from both sides of the valve and reconnect them to an open pipe, to see if the system works better with the valve out of the system. Your heat will be full on with this setup. Finally, I've gotten better heat after flushing the coolant with Prestone superFlush. This involves cutting the intake heater hose and installing the T from the Prestone flush kit, so you can attach a garden hose and get all the old crud out of the system. Then fill with a 50/50 solution of distilled water and coolant.

If none of this helps, then refurbish the heater box.

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