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Dan
Dan, Technician
Category: Jeep
Satisfied Customers: 23591
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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My heat stops working when the fan comes on, blower works.

Customer Question

My heat stops working when the fan comes on, blower works. Have replaced thermostat. Is my engine overheating?
Submitted: 1 year ago.
Category: Jeep
Expert:  Dan replied 1 year ago.

Hello, my name is***** temperature gauge show vehicle to be overheating? Have you checked coolant level? It just blows cold air? Thanks.

Customer: replied 1 year ago.
Cooling level is fine. Temp gage fine. But I have noticed that I lose heat when the cooling fan comes on.
Expert:  Dan replied 1 year ago.

When the cooling fans come on the gauge drops or interior heat gets cool?

Customer: replied 1 year ago.
Right. When cooling fan comes on, no heat. As soon as the fan stops... Heat comes back on. Gauges remain on normal.
Expert:  Dan replied 1 year ago.

Does the heat seem to be as warm as it should be before fan kicks in or is it still pretty cool? Does gauge actually drop when fan kicks on?

Customer: replied 1 year ago.
The heat gets warm enough, but when the fan comes on it stops and blows cool air. When the fan stops the heat returns to normal. Temp gauge stays the same throughout. But now check engine lit is also on
Expert:  Dan replied 1 year ago.

It sounds like a thermostat problem or thermostat housing. Do you know what code you are getting now? Also, what size engine do you have? Thanks.

Customer: replied 1 year ago.
Just replaced thermostat
Expert:  Dan replied 1 year ago.

Do you know what codes your getting? And what engine do you have? Thanks.

Customer: replied 1 year ago.
Unknown as to the codes. I have one but have no idea how to use it.
Expert:  Dan replied 1 year ago.

If you turn key on-off-on-off-on within 5 seconds code should display on odometer. Here is a video showing how.

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https://www.youtube.com/watch?v=Qul9HC-FDCg

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Customer: replied 1 year ago.
Have tried this couple of times. Each time it says done then the engine icon flashes. Then it goes back to miles.
Expert:  Dan replied 1 year ago.

Ok, the check engine light and heat problem is most likely unrelated anyways. Since thermostat has already been replaced next step is to flush out the heater core. If heater core is clogged it will cause this problem. You can disconnect both hoses going into firewall then use a garden hose to flush it out from both directions. To have this done at a shop would cost around $150. As far as the check engine light you can have diagnostic codes checked at your local parts store for free, write them down, and let me know what they are. Let me know how it goes or if you have more questions, thanks.

Customer: replied 1 year ago.
Ok. I have appt for service, but not until next week. Is it ok to drive until then?
Expert:  Dan replied 1 year ago.

Yes it will be fine as long as vehicle is not overheating. Let me know how it turns out. Thanks again and have a happy thanksgiving!

Customer: replied 1 year ago.
Thanks. Happy Thanksgiving to u as well
Expert:  Dan replied 1 year ago.

Thanks

Customer: replied 1 year ago.
How will I know if it's overheating? Will it b obvious?
Expert:  Dan replied 1 year ago.

The temperature gauge will go up. Let me know how it goes, thanks.

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