Heater issue, hot to cold to hot....HELP

[sector550]

2003 dual climate control. V8 Limited edition, digital control.

My 4R's heater doesn't blow constant hot air unless I am pushing in the throttle. Once I let off the throttle, it goes back to cool/cold air? Anyone know what this is or can direct me to a link?

Thanks for your help.

 

[cabowally]

Get the FSM. Find the HVAC PROBLEM SYMPTOMS TABLE.




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[ChaosStarter]

Check the coolant level in the resevior and radiator first. Sounds like you're low.

 

[unclebeansie]

Likely need a new thermostat.

When they fail, they normally fail open and allow coolant through the radiator regardless of coolant temperature.

 

[sector550]

Chaos Starter you were right. The coolant was down (way down actually). Filled it up and now its blowing hot air at stop lights/signs. Thanks everyone for your input.

 

[MidwestT4R]

That fact that your coolant was "way down" is a good reason for some follow up.

Is there a leak somewhere? Hoses? Radiator? Any puddles on the garage floor?

Have you pulled your dipstick to examine the oil? Does it look normal or like chocolate milk?

Do you have an idea when you last checked the coolant level and it showed full with fluid in the overflow reservoir?

I ask only because a slow leak from a hose might not be noticeable over time. But if you checked it two months ago and now it's way low you likely have a leak. Checking around a bit might show you that it's just something simple like a hose connection. You certainly don't want a blow head gasket that is leaking coolant into your oil.

If you refilled it today you will want to watch the level closely over the next few weeks or so to see if it changes.

 

[sector550]

Water pump was leaking. We bought the vehicle knowing that the pump and belt had already been replaced but whoever did the actual labor did a crappy job on the gasket and timing belt. So we had to get those replaced One thing after another. Hopefully this is the last thing for a long time....