Heater Issue
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Heater Issue
I just bought a 2001 F-150 with a 5.4 with 120,000 miles on it. Im having a heating issue and Im clueless on how to fix the problem without taking it to ford and having them diagnose the problem. When the truck is at normal operating temperature it blows warm air on the highest setting NOT HOT, I flushed the radiator until only water came out then I filled the radiator until completely full with 50/50 mixture. I had read on here to check the hoses going to the heater core the hose on the Right side is HOT and the left side is WARM. I talked to a Ford Mechanic and he said he bets that there is an air pocket trapped inside. So I raised the front of the truck and let it run for 20 mins at 1800 RPM with the heater turned to the highest setting and still no luck. Im pretty sure the heater core is not leaking I have checked the passenger side under the carpet and it shows no sign of leaking. I heard maybe it could be the blend door, how do I check that without taking the whole entire dash out? How can I flush the heater core? You can barely get to the hoses to take them off. I have no idea and Im hoping I can get some expert opinions on here. Thanks For Reading
Lead Driver
Joined: Sep 2006
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The return hose from the heater should be more than warm.
With the tank cap off and motor off squeeze the top hose using it like a pump to coax the air out while watching for air bubbles that result.
The theromstat should have one small hole in it to help bleed air by it when it's closed.
If you find the core is blocked, try to back flush from the hoses instead of at the core location.
I have replaced my coolant several times and never had an issue doing it this way.
Last time was to replace a thermostat that I found was running too cool at about 185 when it should be about 196 to 200.
Good luck.
With the tank cap off and motor off squeeze the top hose using it like a pump to coax the air out while watching for air bubbles that result.
The theromstat should have one small hole in it to help bleed air by it when it's closed.
If you find the core is blocked, try to back flush from the hoses instead of at the core location.
I have replaced my coolant several times and never had an issue doing it this way.
Last time was to replace a thermostat that I found was running too cool at about 185 when it should be about 196 to 200.
Good luck.
New User
Joined: Dec 2012
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I concur with bluegrass, I have the same problem.I know everything is good in my case except for maybe an air pocket or thermostat.I know the last time I changed my thermostat diagnosing my heater problems I replaced with a 185 and maybe that is not hot enough.
Freshman User
Joined: Feb 2011
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A 195F degrees thermostat is what these trucks should be running, and what the PCM is expecting, FYI.
Freshman User
Joined: Feb 2011
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Sorry, I should have wrote:
A 192F or 195F degrees thermostat is what these trucks should be running, and what the PCM is expecting, FYI.
Sometimes, you will see either of these temp ratings, depending on who manufactures the thermostat. I think the OEM Motorcraft one is 192F, and the aftermarkets are usually rated 195.
185 is below Ford's spec. Which may, or may not be your issue.
A 192F or 195F degrees thermostat is what these trucks should be running, and what the PCM is expecting, FYI.
Sometimes, you will see either of these temp ratings, depending on who manufactures the thermostat. I think the OEM Motorcraft one is 192F, and the aftermarkets are usually rated 195.
185 is below Ford's spec. Which may, or may not be your issue.
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Lead Driver
Joined: Sep 2006
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The temperature needs to be in the 196 to 200 operating range.
The radiator is very large in area and cools fast moving down the road.
The pressure cap is rated at 15 psi and rasies the boiling point of the coolant to well over 225.
At lower temps the motor tends to run richer and has an effect on fuel mileage and cylinder wear over the long term.
The min. temp the PCM will tolerate is 175 before it sets a code for the temp being too low as detected by the CHT sensor.
The same sensor also signals an overheat condition and sends the PCM into Limp mode to try and save the motor.
I can asure that in winter temps below 28, a 185 thermostat will not be enough in most cases to defrost/defog and keep up with cabin needs.
Good luck.
The radiator is very large in area and cools fast moving down the road.
The pressure cap is rated at 15 psi and rasies the boiling point of the coolant to well over 225.
At lower temps the motor tends to run richer and has an effect on fuel mileage and cylinder wear over the long term.
The min. temp the PCM will tolerate is 175 before it sets a code for the temp being too low as detected by the CHT sensor.
The same sensor also signals an overheat condition and sends the PCM into Limp mode to try and save the motor.
I can asure that in winter temps below 28, a 185 thermostat will not be enough in most cases to defrost/defog and keep up with cabin needs.
Good luck.
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New User
Joined: Oct 2012
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If your coolant was very rusty at one time check the water pump. I had the fins rust off of mine and had the same warm cool heater hoses. I also reverse flushed just the heater core. All is hot again.
Dont know how to post a picture yet.
Dont know how to post a picture yet.
Laughing Gas
Joined: Jan 2006
Posts: 1,098
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From: Minnesota
As mentioned, see how hot and hard the top hose is after it warms up. If that baby is not hot, I would replace the thermostat.
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