2005 Heater works Intermittently

[PrettyInCashmere]

My heater is usually blasting cold air recently, but the fact that it does put out warm air on very rare occasions may be a clue as to what is wrong to knowledgeable persons (could be different problem from one that will never put out hot air?)

While I usually run heater on the air aimed only at feet mode, problem is the same in all settings including Auto

Coolant level is where it should be and free of air pockets

Any thoughts appreciated

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[Gus Gutz]

The dual coolant control valve is bad. At least it is in my car with the same symptoms.

 

[Hemi Bob]

My heater is usually blasting cold air recently, but the fact that it does put out warm air on very rare occasions may be a clue as to what is wrong to knowledgeable persons (could be different problem from one that will never put out hot air?)

While I usually run heater on the air aimed only at feet mode, problem is the same in all settings including Auto

Coolant level is where it should be and free of air pockets

Any thoughts appreciated

When I had the same symptoms after purchasing mine, it turned out to be a cracked thermostat housing.

 

[BluByeU]

Don't understand how a cracked thermostat housing would cause similar situation without leaking coolant

The very fact that hot air is blowing in the cabin when ac is selected indicate the dual control valves mounted on the passenger side of the radiator, about half way down have failed. There is two valves sold as a unit, about $170.00. The valves open & close electrically allow heated coolant into the heater to mix with the AC cooled air to provide the cabin with the temperature selected.
The removal/replacement of this dual valve unit is very straight forward, a little time consuming but not difficult.

 

[Gus Gutz]

Don't understand how a cracked thermostat housing would cause similar situation without leaking coolant

The very fact that hot air is blowing in the cabin when ac is selected indicate the dual control valves mounted on the passenger side of the radiator, about half way down have failed. There is two valves sold as a unit, about $170.00. The valves open & close electrically allow heated coolant into the heater to mix with the AC cooled air to provide the cabin with the temperature selected.
The removal/replacement of this dual valve unit is very straight forward, a little time consuming but not difficult.

If been putting this off for a year. The new valve is sitting in the box in the trunk of my car

 

[PrettyInCashmere]

As to putting off cracked thermostat housing, know that mine let go last week. Loss of coolant was so rapid, I could not have driven more than a mile or so.
Did get it to service station (luckily) and had a new one put on. If you already have the part .. I suggest getting it changed ... and not have it split wide open when it chooses to creating an emergency situation
No change to heater problem after this repair.

 

[PrettyInCashmere]

.... The very fact that hot air is blowing in the cabin when ac is selected indicate the dual control valves mounted on the passenger side of the radiator, about half way down have failed. There is two valves sold as a unit, about $170.00. The valves open & close electrically allow heated coolant into the heater to mix with the AC cooled air to provide the cabin with the temperature selected.
The removal/replacement of this dual valve unit is very straight forward, a little time consuming but not difficult.

Seems you are addressing an ac problem if I understand correctly?? My problem is cold air blowing into the cabin no matter what setting I select

 

[BluByeU]

No I am not. If the dual valves never operate than hot or warm coolant will not be diverted to the heater.

 

[PrettyInCashmere]

No I am not. If the dual valves never operate than hot or warm coolant will not be diverted to the heater.

Aw. Thanks. That looks like it would be the problem.

 

[Gus Gutz]

Aw. Thanks. That looks like it would be the problem.

I found the valve online, new, for 40 dollars. I think someone in this forum posted a link to it. Ford wants 300 bucks and another 400 to install it. It's in a hard to get to location and with my 02, I have to move the hydraulic fan pump to get access to it.

 

[05Dave]

Heating or cooling issues are usually related to the coolant control valve as others have commented here. The service manual has a list of tests to rule out computer and wiring issues, but the way Ford designed the system, if you have constant heat or constant cool, I would definitely change the coolant control valve as it can stick open or closed. Closed will cause only cold air from ducts, stuck open will cause only heat from ducts which is my current issue.

 

[Gus Gutz]

Heating or cooling issues are usually related to the coolant control valve as others have commented here. The service manual has a list of tests to rule out computer and wiring issues, but the way Ford designed the system, if you have constant heat or constant cool, I would definitely change the coolant control valve as it can stick open or closed. Closed will cause only cold air from ducts, stuck open will cause only heat from ducts which is my current issue.

Mine is stuck closed. I get cold air all the time. Great in the summer but driving at night with the air on it gets cold in my car. I have the valve but have been putting this off for a year now.

 

[05Dave]

Mine is stuck closed. I get cold air all the time. Great in the summer but driving at night with the air on it gets cold in my car. I have the valve but have been putting this off for a year now.

I have not changed mine yet, but I went through the service manual carefully and arrived at the conclusion that is was the control valve. Doesn't look like any easy place to work. I usually take the car to Ford for annual service and issues, so will probably leave it till next spring as the car will be going into winter storage soon. The problem has been intermittent for a couple of years, but Ivwas always able to correct it by turning the system completely off then back on till now

 

[PrettyInCashmere]

Mine had been intermittent, but only rarely warm air - now constantly cool air

Thank you to all who contributed above

I shall have the valve replaced after electrics are checked

 

[05Dave]

My heater is usually blasting cold air recently, but the fact that it does put out warm air on very rare
occasions may be a clue as to what is wrong to knowledgeable persons (could be different problem from one that will never put out hot air?)

While I usually run heater on the air aimed only at feet mode, problem is the same in all settings including Auto

Coolant level is where it should be and free of air pockets

Any thoughts appreciated

I don't have access to my service manuals where Ivan for a few weeks, but from memory the service manual walks through verifying that the heat/AC control computer is doing its thing properly, then looks at the dual coolant control valve. Ours had intermittent proper control before it quit completely. Occasionally I would cycle the system off and on to getvut to pick up. The coolant control can either stick on or off. There is a relay that interfaces between the computer and the coolant valve which could also fail. The system often switches the ground so one needs to follow the service manual when trouble shooting.
Hope that helps.

 

[PrettyInCashmere]

Thanks - does sound likely the 2 way valve - but checking electrics and relay first is good plan