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Heater problems?

Tiny
JDOHENY48
  • MEMBER
  • 2008 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 187,000 MILES
I am having trouble with my heater not working very well and my temperature gauge is acting funny. Driving the car the heater blows cool air for a while and then the temperature gauge goes up to almost hot but not overheating, the fans kick on, temperature gauge drops to almost cold then the heater starts blowing hot an the temperature gauge moves back to normal position and then the heater starts to blow cool again. The guy I bought it from said he replaced the thermostat so I checked to make sure and it does look new to me. I believe I burped all the air out of the system. But I am still having issues.
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Tuesday, December 11th, 2018 AT 5:20 AM

18 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

From your description, it sounds like you may have a failed head gasket. When it fails, it leaks air into the cooling system and the result is no heat and the temperature jumping all over the place.

https://www.2carpros.com/articles/head-gasket-blown-test

and this guide and video can help if its not a head gasket.

https://www.2carpros.com/articles/car-heater-not-working

and

https://youtu.be/SNRb6pSwYuU

Failed head gasket is a result of overheating which may have been a issue prior to your purchase. The previous owner may have neglected to tell you this.

You would need to do a leak down test on all the cylinders. That is when you removed the plugs and add shop air into the cylinder and watch for movement in the cooling system. That will confirm which cylinder.

Roy
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Tuesday, December 11th, 2018 AT 7:22 AM
Tiny
JDOHENY48
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  • 3 POSTS
Awesome, thanks for the reply Roy! I will see what I can come up with in the meantime. Would a water pump also be something to consider?
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Tuesday, December 11th, 2018 AT 9:13 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
I doubt it. If it was the water pump, it would overheat all the time.

Roy
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Tuesday, December 11th, 2018 AT 9:14 AM
Tiny
JDOHENY48
  • MEMBER
  • 3 POSTS
After further investigation I have concluded that it is a blown head gasket! I never preformed a leak down test on it but it does have exhaust gasses and blew coming up from inside the coolant reservoir and there is milky coolant looking sludge underneath the engine oil cap.
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Tuesday, December 11th, 2018 AT 1:35 PM
Tiny
ASEMASTER6371
  • MECHANIC
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There you go. Good find.

My concern is the milky oil. Coolant in the oil is bad. The coolant gets on the main and rod bearings and damages the babbit material on the bearings causing excessive wear.

If you are going to pull the heads, I recommend replacing the mains and rod bearings.

Roy
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Tuesday, December 11th, 2018 AT 1:38 PM
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2007 FORD EXPLORER
  • 10,700 MILES
Heater is blowing out cold air, what could this be from
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Sunday, September 27th, 2020 AT 11:29 AM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check for a vacuum leak to heater control valve it's underhood fi both hoses hot then check temp actuator on lh side of heater, pic included.
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Sunday, September 27th, 2020 AT 11:29 AM (Merged)
Tiny
PAUL PERNICANO
  • MEMBER
  • 1 POST
  • 2007 FORD EXPLORER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 66,000 MILES
My middle cool/heat select switch when I put to heat won't engage the damper? Just sit and clicks I beleive it's defective
how can I test and or replace? P.S if I leave it in the cool position it doesn;t click and I get cooling but no heat when in hot range
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
The heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
TMALO
  • MEMBER
  • 3 POSTS
  • 2007 FORD EXPLORER
  • 61,000 MILES
No heat no matter how long I let my 07 warm up I don't get any heat till I start driving
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,650 POSTS
Make sure the coolant level is full. When the engine is hot and running with the heater on, feel both heater core hoses. Both should be hot. Let me know what you find.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Sounds like a circulation issue. Make sure the thermostat is working correctly. Check the level and lastly, the heater core may be clogged.

Roy
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
CDHERN68
  • MEMBER
  • 1 POST
  • 2006 FORD EXPLORER
  • 42,000 MILES
Within the last couple of cold days the heater has been working intermittently. It sometimes only blows out cold air. Sometimes hot. When it's blowing out cold air turning it off and back on again sometimes gets it blowing hot air again.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,650 POSTS
Make sure the coolant level is full. Check to make sure the engine is running at a normal operating temp. If both are good, check to make sure the blend air door is functioning properly.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
OLOPEZ
  • MEMBER
  • 1 POST
  • 2005 FORD EXPLORER
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 10,000 MILES
Enter your question.I have a 2005 ford explorer and my heat in the front is throughing out cold air?What is wrong?And how much to fix? It also makes a clanging noise when put on?
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,650 POSTS
It sounds like the blend air door isn't working or the linkage on it has come loose. Check that. As far as a price, I would need to know what is actually wrong with it before giving an estimate.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
ORITHEONH
  • MEMBER
  • 1 POST
  • 2005 FORD EXPLORER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 70,000 MILES
When I turn the heat on I can hear faint knocking sounds coming from the dashboard. The heater only blows cold air. The air conditioner works fine. What could the problem be?
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,650 POSTS
That sounds like the blend door is sticking. It determines if you get AC or heat into the vehicle. If it is stuck in the wrong position, you won't get heat.

The blend door is located near the heater core and isn't too easy to access. However, I feel confident that is the problem.
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Sunday, September 27th, 2020 AT 11:30 AM (Merged)

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