Ok I got the interior lights problem solved
Thread Starter
Senior Member
Joined: Sep 2013
Posts: 518
Likes: 3
From: Santa Cruz Ca.
Year: 2000 WJ
Model: Grand Cherokee
Engine: 4.7
I am embarrassed I even asked here. It was a simple adjustment on the "control switch" that runs everything else. What I have now is luke warm heat coming from the heater. Engine temp is normal, blower works and it appears that all the vent settings work. Air just is not hot. Warm but not doing the job of heating the inside.
Is there a module or relay or something I need to look for.
Thanks again
Is there a module or relay or something I need to look for.
Thanks again
CF Veteran
Joined: Aug 2011
Posts: 1,031
Likes: 4
From: Blue Springs, MO
Year: 1993
Model: Grand Cherokee
Engine: 4.0L Laredo
No idea what model you have but assuming it's a Jeep, you might check for proper operation of your blend door.
Some models have a vacuum controlled valve that opens/closes to let water into the heater core. Most say to bypass it and plug the vacuum line.
That's all I got. Good luck!
Some models have a vacuum controlled valve that opens/closes to let water into the heater core. Most say to bypass it and plug the vacuum line.
That's all I got. Good luck!
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
You might want to back-flush the heater core with a garden hose, DO NOT USE AN AIR HOSE!!! The hot water supply hose from the thermostat housing should be the bottom hose. this allows air to escape into the water pump. If your WJ is like mine, it has a full-flow heater that allows hot water to flow through the core at all times.
If you're using hard water in your coolant mix, you could have calcium deposits in the core. I have well water and when I had heater problems with my ZJ, I had to run a gallon of CLR in my coolant for a couple of days to clean it out. Since then, I buy premix.
Suggestion; Put your location and vehicle in your signature so people know what you're working with. It saves a lot of questions, unless you want to remain mysterious.
If you're using hard water in your coolant mix, you could have calcium deposits in the core. I have well water and when I had heater problems with my ZJ, I had to run a gallon of CLR in my coolant for a couple of days to clean it out. Since then, I buy premix.
Suggestion; Put your location and vehicle in your signature so people know what you're working with. It saves a lot of questions, unless you want to remain mysterious.
Last edited by dave1123; Mar 20, 2014 at 06:23 PM.
Thread Starter
Senior Member
Joined: Sep 2013
Posts: 518
Likes: 3
From: Santa Cruz Ca.
Year: 2000 WJ
Model: Grand Cherokee
Engine: 4.7
Its a Laredo. And right now my location is "on the run". Actually I live in Hawaii. My 2000 Laredo is a recent purchase in California where I am working on a house with a friend. I will be going back to Hawaii shortly. Right now I am sleeping on the floor of the house and I am in a McDonalds using their wifi. I have heard about these bower door problems and when I bought the vehicle. I checked the heater first to see if it was working. It was very warm that day in Campbell and I thought the air was hot. Bought the vehicle and took it over to the coast in Santa Cruz. It was 49 degrees the next morning and the air from the heater was luke warm as opposed to the day before when the ambient temp was 87. So do I have a blender door or vacuum switch?
Really appreciate your help and sorry I didn't provide clear info.
Really appreciate your help and sorry I didn't provide clear info.
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
The blend door controls where the heat goes, as in windshield, dash, or floor, and combinations. If the shaft breaks, it will sometimes block the fan's output so you get lots of fan noise, but only a slight breeze from the heater.
I've been told, but haven't checked yet, that the accuators on the WJ are electric, not vacuum. It seems the vacuum motors were too violent and that's what snaps the shafts. I think I have an air inlet door problem on mine, because if I put the heater on recirculate, I get blasted with furnace heat, but only lukewarm heat otherwise.
I've been told, but haven't checked yet, that the accuators on the WJ are electric, not vacuum. It seems the vacuum motors were too violent and that's what snaps the shafts. I think I have an air inlet door problem on mine, because if I put the heater on recirculate, I get blasted with furnace heat, but only lukewarm heat otherwise.
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