99 Jeep Cherokee-Dual-Zone Climate Control only works on one side.

[DonTom]

99 Jeep, 4.7L- Grand Cherokee Limited Edition (my other old Jeep, this is NOT the one that I just had the A/C repaired in

This 99 LE Jeep has separate heater (and A/C) controls for passenger and driver. A/C works fine on both sides. But when I turn on the heat on both sides, including the window defogger, it blows hot air on the passenger side but blows cold air on the driver side, at the same time, with both controls at the same setting (includes all the way to max heat on both sides). I cannot get any heat at all from the driver's side, but the blower is at normal speed (but with cold air instead of warm). Even if I only oprate the left side, I get no heat. Heat is always fine on the right side.

This vehicle only has one heater core, so how is this possible?

It's a rather serious problem because I cannot use the window defogger on the driver side, where it is needed the most.

I just hope to have it fixed before the cold weather comes. But I don't have a clue where to start.

-Don- Reno, NV

[Dave Brand]

This vehicle only has one heater core, so how is this possible?

The desired temperature will, I assume, be obtained by mixing hot air from the heater core with colder air. There will be a diverter flap to mix air as need. It sounds as though something's failed which is preventing the flap from moving - could be the flap itself is stuck, a problem with the linkage from the actuator to the flap, a failed actuator or maybe some other fault.

I hate to say this, but it looks like you're going to have to delve into the heater unit - on most vehicles that's a nightmare of a job!

[Ken]

Hope this might be of some help, Don. It seems to be a common problem with the JGC of that era.

http://www.denlorstools.com/autoblog...d-door-repair/

Best of luck with your repairs.

Ken.

[DonTom]

Ken,

Thanks a billion! I wasn't expecting any help here on that one, so glad I was wrong. I will order the stuff and do the conversion to non-separate heat.

-Don- Reno, NV

[Ken]

Ken,

Thanks a billion! I wasn't expecting any help here on that one, so glad I was wrong. I will order the stuff and do the conversion to non-separate heat.

-Don- Reno, NV

Glad to help, Don. Hope it all goes smoothly.

Ken.

[DonTom]

Glad to help, Don. Hope it all goes smoothly.

Ken.

It's only supposed to take about an hour to install. Mine is already on its way, was shipped out today.

I will report back here after it is installed.

-Don-

[DonTom]

1999 Jeep Grand Cherokee, Limited Edition, 4.7L

Job is completed, but not by me. The stuff came in the other day. The instructions included info. to check for the door error codes. Mine had three error codes for the doors, 52, 54 and 56.

52=not listed on their sheet. But web search says it means "AI (Recirc) door travel range too large".
54=left temperature door travel too large.
56=right temperature door travel too large.

But after reading the instructions and viewing the you-tube and such, I decided to let somebody else do this job. The Heater Treater company recommended several places near here to install it for me. The first place I called was here in Reno, who has done many of them. But they were so busy, they could only schedule me in late next week and they had no room to hold any more vehicles.

So I called the next place, 30 miles away in Carson City, with the name of "Performance Auto Care". They said they have never done one, but they do know how to do it. But they could do it right away. So I took a chance with them. And it works perfectly. No complaints. A fairly large place that does RV's and more and seems to have a lot of employees as well as room.

The item cost about a hundred bucks. It cost $255.00 to have it installed. So the total price to get the job done was ~$355.00.

They gave me back my old parts. Cheap plastic rod broke on the cheap crap OEM dual door. The Heater-Treater single door uses a strong metal rod at that same place which I could not break if I tried. Since this is a single door, the Jeep no longer has useable dual temp controls, which is no issue to us. It simply now works the way most vehicles work, instead of having separate temperature controls for driver and passenger. Now the right side temp control for the passenger does nothing, as stated it now should be, with the Heater-Treater instructions.

Now I can get warm air for my defroster as well as warm air on the driver's side, unlike before where it only had warm air possible on the passenger side.

But warm air won't be needed here for a while, as this is still A/C weather here. But not having a window defogger can be dangerous at times.

-Don- Reno, NV

[Ken]

Glad it all worked out OK, Don.

Ken.