No Heat and tried everything we could think of!

This car has been in the family since it was new. About 2 years ago the heat on the passenger side vents stopped blowing hot air and started blowing cold. Which was okay for me cause i was the driver. This year when it got cold again and i turned on the heat, there was none on the drivers side either, only cold air. I brought it to my local shop who usually are very good. They tried to fix the blend air door, flushed the cooling system and a number of other things (at no charge) and still no heat. I live in NY and it’s just getting colder. any ideas???

What year and make is it. 4.0 Liter?

2001 Jeep Grand Cherokee 4.7 Liter

This might be an interesting read. I might take it one step cheaper and manually set per season.

tried the blend air doors… no luck

New blend doors? The exterior controls may look like they are working but the unseen door is not. What was the try? It looks like it describes the symptoms.

I would take a better look at the link. Theres all kids of info in there. Looks like you can do some hands on investigating and probably find the bad blend doors your self which is what it sounds like it is. Under the dash through the glove box…Check out the link

It seems that the problem with the blend air door has to do with heat delivery to the passenger side of the cabin, not the whole system. If the heater core is not circulating hot fluid, there is no heat to transfer. When you turn on the heater fan, the cool air blows across the radiator and transfers heat into the cabin. You should be getting some warm air, somewhere, if the heater core is properly circulating fluid. My guess is that it is not. I think you have a clogged up and failing heater core.
You can test this by checking the temp gauge before and after you engage the heat and turn on the heater fan. If the fan is blowing and the heater core is okay, the temp gauge should drop a little while the fan is running. Similarly, if the heater core is not circulating fluid, the whole system will run a little hotter in general and will not cool at all while the heat is on and the fan is running.

Locate the hoses to the heater core under the hood. Drive the car until the engine is warmed up with the heater on. Feel the heater hoses. If one is hot and the other is cold, the heater core is blocked. If both are hot, then you may have a problem with the blend doors. If both are cold, you have no coolant going to the heater core.

if you have never changed the coolant it could be the heater core is clogged up with sediment.

If there is no heat in the defroster mode and the air gets directed to the windshield then it would seem there is a heater core problem. If that mode works ok then maybe there is a vacuum line problem to the air box door. I think there is a seperate door in the air box for the AC and heat modes and perhaps it is stuck in the AC position somehow.