heater help..
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Joined: Nov 2008
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heater help..
alritei have a 90 f-150 4x4 has a/c..
truck does not blow hot air.. it blows a luke warm air, and means its incrediblly cold out for this time of year.. needs to change!
so eitehr..
1. Heater Core
2. a blend door isnt closing.
3. the heat on this body style truck isnt that great... had 3 of them in the family... and only 1 of the 3 had good heat.
but i guess my question what do you guys think it is?
also. under the hood. passengerside near the firewall.. there is this vaccum valve that appears that it open/closes the guessing freshair or a blend door? what is this excatly? and which way does it need to be for HEAT! in or out?
anythings i can look for else wise.. going to flush heater core tomorrow..
how big of a pain is it to replace the heater core on this truck?
remove glove box and will the box open enough o get it out and look inside?
truck does not blow hot air.. it blows a luke warm air, and means its incrediblly cold out for this time of year.. needs to change!
so eitehr..
1. Heater Core
2. a blend door isnt closing.
3. the heat on this body style truck isnt that great... had 3 of them in the family... and only 1 of the 3 had good heat.
but i guess my question what do you guys think it is?
also. under the hood. passengerside near the firewall.. there is this vaccum valve that appears that it open/closes the guessing freshair or a blend door? what is this excatly? and which way does it need to be for HEAT! in or out?
anythings i can look for else wise.. going to flush heater core tomorrow..
how big of a pain is it to replace the heater core on this truck?
remove glove box and will the box open enough o get it out and look inside?
Senior Member
Joined: Jul 2007
Posts: 3,805
Likes: 480
From: Cape Girardeau MO
The vacuum valve under the hood is the fresh air / recirculation damper. Ugh - it's been a few years since I fooled with it - but thinking that the valve fully out would be fresh air - that is, a vacuum applied would cause recirculation. Shouldn't matter a great deal which way this is oriented for heat, however, if in the recirc position - may have issues with condensation and fogging in the cab.
Be sure not to overlook other potential causes - such as a low coolant level or a kinked heater hose or a stuck-open thermostat. The goal is to obtain maximum possible flow at operating temperature through the core.
Not sure of the issues you've had with heaters in the various trucks - mine will run me out of the cabin.
Since our model years are close - am assuming that your blend door is also controlled by cable instead of vacuum motor. If so, may want to check the cable adjustment to make sure the damper is fully seating off. There is a clip accessible behind the glove box for adjusting the cable housing - pretty crude setup - move the cable housing, then set the clip. I make sure I hear a good damper door 'thunk' when I slam the temp lever to heat.
Replacing the heater core on our generation would rate as one of Ford's 'better ideas', IMO. Remove the glove box - you will see an access door. About 8 screws out, and you have full, clear, and unobstructed access to the core. As I've mentioned in other threads, you will likely spend more time rounding up the tools and putting them away than you will with the actual replacement.
If you choose to replace the core, recommend to get the 'better' of the selections available - my experience has been that the cheapies just don't put out the heat - which affects both the potential cab temperatures and most certainly the defroster capabilities. Ballpark numbers are that the $20 cores are the cheapies, while the $40 and up selections are the 'better's and 'best's. My personal 'acid' test is to take a look through the fins - if you can't see daylight across/through the whole surface - it's not going to put out the maximum possible heat - again, my experience has been that the cheapies have part of the area blocked off.
Be sure not to overlook other potential causes - such as a low coolant level or a kinked heater hose or a stuck-open thermostat. The goal is to obtain maximum possible flow at operating temperature through the core.
Not sure of the issues you've had with heaters in the various trucks - mine will run me out of the cabin.
Since our model years are close - am assuming that your blend door is also controlled by cable instead of vacuum motor. If so, may want to check the cable adjustment to make sure the damper is fully seating off. There is a clip accessible behind the glove box for adjusting the cable housing - pretty crude setup - move the cable housing, then set the clip. I make sure I hear a good damper door 'thunk' when I slam the temp lever to heat.
Replacing the heater core on our generation would rate as one of Ford's 'better ideas', IMO. Remove the glove box - you will see an access door. About 8 screws out, and you have full, clear, and unobstructed access to the core. As I've mentioned in other threads, you will likely spend more time rounding up the tools and putting them away than you will with the actual replacement.
If you choose to replace the core, recommend to get the 'better' of the selections available - my experience has been that the cheapies just don't put out the heat - which affects both the potential cab temperatures and most certainly the defroster capabilities. Ballpark numbers are that the $20 cores are the cheapies, while the $40 and up selections are the 'better's and 'best's. My personal 'acid' test is to take a look through the fins - if you can't see daylight across/through the whole surface - it's not going to put out the maximum possible heat - again, my experience has been that the cheapies have part of the area blocked off.
Thread Starter
Junior Member
Joined: Nov 2008
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well.. the truck is running normal temp..
both heater core hoses are hot.. .. so that is what is making me think a blend door not working quite rite...
its full on coolant...
so idk.. going to dig into it more tomorrow... thanks for ur help...
might just replace the thermostat... but is there enough room to change it w/o pulling the waterpump? i know the last one of these i put a waterpump in.. put a thermostat in simply b/c it looked like it would b a pain with the pump in. my truck has the 5.8
both heater core hoses are hot.. .. so that is what is making me think a blend door not working quite rite...
its full on coolant...
so idk.. going to dig into it more tomorrow... thanks for ur help...
might just replace the thermostat... but is there enough room to change it w/o pulling the waterpump? i know the last one of these i put a waterpump in.. put a thermostat in simply b/c it looked like it would b a pain with the pump in. my truck has the 5.8
Senior Member
Joined: Jan 2008
Posts: 1,254
Likes: 4
From: Pablo MT
It will be a pain to changes without removing the water pump, get a flexible handled nut driver and quarter inch socket the size you need, you will have to break them free with a end wrench. If you get the universal auto parts store thermostat it will have a round instead of oblong flange, this means that you will not be able to twist it to lock into place, I found that some superglue will hold it into the housing until it get up to temperature then the glue will break down and not hold it in if you need to replace it in the future.