Jeep Laredo 2003 heater blowing cold air

[cmllamas]

My 2003 Jepp Lardo is blowing cold air when I turn on the heater. I don't have any money to pay for repair. I'm a cancer patient and I need the car, the weather is getting cold. Please help me.

[Bob D.]

Are you capable of working on the vehicle yourself?
If not I would suggest buying an electric heater that plugs in to the cigarette lighter, JC Whitney, Pep Boys, etc. should carry them.

[mkvapil]

Do you have dual climate control? It is possible that a recirculation blend door is stuck on vent which let in outside air(cold) and its very costly to repair($900).

[CAFB 04-12]

Bump. I'm having the same issue with my 2003 Jeep Grand Cherokee Laredo. It doesn't have the dual climate control, it blows hot air for the first 5 minutes after the engine warms to normal then blows cold air. It's intermittent, though, which is confusing me. The coolant levels are normal.

Is this a problem with coolant flow through the heater core?

[pkucan]

Is the heater hose from the engine going thru the firewall hot? If so then it is a blend door problem or limited circulation in the heater core. If the hose is only luke warm then it is a thermostat stuck open or a blown head gasket.

[CAFB 04-12]

Both top and bottom hoses are pretty hot. Not sure which is the input and which is the output though. Here's some context:





I'm also getting OBD-II codes (using the ignition on/off technique) P0122 and P0123 (which are either Accelerator Position Sensor (APPS) Signal Voltage Too Low and Accelerator Position Sensor (APPS) Signal Voltage Too High or Throttle/Pedal Position Sensor/Switch A Circuit Low Input and Throttle/Pedal Position Sensor/Switch A Circuit Intermittent according to wjjeeps.com

I'm also getting a P0455 code which has been on for awhile and I think is unrelated (Evaporative Emission Control System Leak Detected [large leak]).

I went out this evening to do some checking. I let the Jeep warm up to normal temperature and ran the heater on high with the fan on high. I had it first set to defrost and got hot air. I switched to the panel and the air soon went cold. I fiddled with the thermostat control and the heat came back on. I continued to move the thermostat to see if the air would get cooler then hotter when moved in those directions. It responded normally. The confusing thing is the intermittent nature of this problem.

What does the blend door do? I'm guessing it combines the hot air from the heater core with cool outside air to create the temperature demanded by the thermostat. Is this correct? Is there a better way to tell if it is sticking and not allowing hot heater core air to mix with the cold air?

How can I check for good flow through the heater core?

Thanks for you help.

[CAFB 04-12]

Double post. Sorry.

[GRABAWRENCH]

I reciently ran into the same problem with a 2002. The blend door broke and allowed cold air into the cabin. Garage wanted over 1000.00 to fix. I did some research on this problem and for a product called heater treater. Found on ebay for 125.00. Took @ 45 min to complete repair and was real easy. Got a backyard mechanic for a friend? Check it out. Wish i could help otherwise. Sorry to hear about the cancer. Be strong and trust god. All will be well. God bless and good luck with both.