The All Too Common Heater Problem
New User
Joined: Jul 2003
Posts: 11
Likes: 0
I am having the oposite problem righ tnbow... stuck on full heat.
I've learned that there are 2 doors we need to be looking at. The first one can be seen when looking at the squirlecage fan. it is either open or closed (no in between) it determines if you are pulling in fresh air or recirculating inside air. The second door is inside the climate control system, (I think near the heater core... going to open it up tonight) and it controls the ratio of hot:cold air.
The temp control on the dash is a resister (I've opend it up to look) and I believe it controls a stepper motor the turns this flap insite the unit. it basicly moves from covering the heat duct (cold open 100%) to coverint he cold duct (heat 100% open).
The cold air is jus tht eoutside air. This air passes through the A/C evaporator (if you have A/C) so when the A/C is turned on it cools the incoming air even more. If the A/C is off then it is the same temp as outside.
I've learned that there are 2 doors we need to be looking at. The first one can be seen when looking at the squirlecage fan. it is either open or closed (no in between) it determines if you are pulling in fresh air or recirculating inside air. The second door is inside the climate control system, (I think near the heater core... going to open it up tonight) and it controls the ratio of hot:cold air.
The temp control on the dash is a resister (I've opend it up to look) and I believe it controls a stepper motor the turns this flap insite the unit. it basicly moves from covering the heat duct (cold open 100%) to coverint he cold duct (heat 100% open).
The cold air is jus tht eoutside air. This air passes through the A/C evaporator (if you have A/C) so when the A/C is turned on it cools the incoming air even more. If the A/C is off then it is the same temp as outside.
Elder User
Joined: Dec 2002
Posts: 559
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From: South Carolina
This issue has nailed me before - with heater cores and radiators. They're both heat exchangers, and they both get less efficient with age. Even if you don't have rust pudding in them, scale and debris builds up slowly and eventually transfer of heat from the coolant to the air blowing through the core just slows down. With normal use, it's my opinion that radiators should not be used more than 10 years, regardless of external condition. Heater cores are inexpensive and easy to install - I'll be a new heater core will correct this problem.
New User
Joined: Jan 2005
Posts: 17
Likes: 0
My 93 aerostar had the same problem. Blend door opened and closed fine, thermostat was good, heater hoses to and from the core were hot. Replaced the 6 month old heater core and got heat - finally. Recommend, THOROUGHLY flushing the system, engine block and all, while by-passing the heater core. This way you know when you put in the new one, there won't be anything to cause the core to get plugged, or slightly plugged. Just my $.02.
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