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Cherokee XJ 93 heater blowing cold

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Old 05-12-2017, 09:06 PM
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Default Cherokee XJ 93 heater blowing cold

Hi,

So I have read through lots of threads but need some clarity for my situation.

My heater does not work, cold air at full blast.

I have flushed the core today, and then I flushed the whole coolant system.

It is still cold.

One pipe into firewall is hot, the other is cold. Does this mean I didn't flush it enough?

Also, I did have some work done on thermostat a while back, now it runs pretty cold.

From what I can see it could be: the core, the thermostat or the blender...

I can hear the actuator on the blender so I guess that is working.

Any help appreciated!

Matt.
Old 05-13-2017, 02:41 AM
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Sounds like heater control valve issue.
Old 05-13-2017, 07:41 AM
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Good possibility.
Old 05-13-2017, 08:01 AM
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Originally Posted by MattR
One pipe into firewall is hot, the other is cold. Does this mean I didn't flush it enough?
Possibly. Disconnect the hoses behind the heater core valve (you want the valve out of the picture for this test) and see if you can blow air through the heater core.

If the heater core is plugged, you'll know it.

If air flows freely, it's probably the valve. Here's the cheap and easy fix:

Buy about 5* feet of 5/8" heater hose, and about 5 feet of 3/4" heater hose, and some new clamps. Remove the old hoses AND the control valve. Toss them in the trash. Replace with the hose. Cap the vacuum line that used to control the valve. Done.

You don't need that valve. Chrysler got rid of it on later models because it's nothing but trouble.

Originally Posted by MattR
Also, I did have some work done on thermostat a while back, now it runs pretty cold.
You didn't make the mistake of using a colder thermostat, did you? Factory is 195, and that's what these beasties like.


Also, what brand did you buy?



*You don't need the full 5 feet, but if you have extra, you can route it the way you want it. Better yet, buy 10 feet of each. It's cheap, and you never know when it will be handy.

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