[dlightful zj]

I have a 98 5.9. My question is about the heater/AC. It seems that they are both running at the same time.In the summer you get cooler than ambient air (not by much) and in the colder weather you get colder air. There is not a smell of coolant when you turn either on, and there isn't any antifreeze leaks. The air conditioner is fully charged. Where can I go from here.

 

[dondandd]

This sounds almost like a blend door problem....... First, if you are not loosing coolant, this smell might not be a problem..... sometimes if the coolant overflow reservior has leaked a little coolant in the engine compartment, you can smell it, because the reservoir is near the firewall and near the outside air intake. If you start noticing a big increase in coolant smell or loss of coolant, then worry!

As far as the other problem..... during the summer, with the A/C on, and the temp set to cold, it will not blow cold air? If you set the temp to hot, will it blow hot air in the summer?

In the winter... if you set the temp to hot, will it blow hot air and if you set it to cold, will it blow cold air?

Do you have the automatic climate control or the manual control?

The A/C will run if you either turn on the A/C button, or you have the controls set to defrost.

Just a little more info might help.
Don.

 

[dlightful zj]

It has the automatic climate control. In the summer the air is warmer than in the winter just because of the outside temp. And just the oposite in the winter.

 

[dondandd]

It still could be the blend door, but I'm also not quite seeing the problem yet.

And.... on second reading.... I completely missed the NOT a smell of coolant! Ooops, ok so not a leaking heater core.... good.

But back to the real problem... ok, so lets say its summer time, you crank the temp to cold and you say you get get "cool" air, but not cold. My first thought is your A/C isn't charged properly.

Now, its winter time, obviously a poorly charged A/C might seem to work better since the outside is cold. But, if you crank the temp up, does the air get hot?

I'm trying to understand if the blend door is operating properly and changing between cold and hot, or if there is another issue.

Don.

 

[dlightful zj]

I would have to say it is the blend door. The AC is fully charged. The thernostat is godd also.
How does the door work? How would I check to varify the operation of it? If it doesn't work what are some repair tips?

 

[dondandd]

Your best bet is to follow a Factory Service Manual (FSM), which has instructions on how to put the ATC into test mode and run through different tests. I have a FSM for 1993, but I'm not sure if it is the same procedures for a 98..... plus, the procedures span a couple of pages and include a bunch of tables, diagrams and stuff. The test modes allow you to tell the system to move the blend door to see if it moves, and then it can test to be sure the feedback system is working properly.

If you can narrow it down for sure to the blend door.... my guess would be on the blend motor itself, which would be replacement. Although this is for sure going beyond anything I've dealt with before.

You might try to search the forums here and on JU for any information pertaining to the automatic temperature control, or blend door issues, or anything like that.

Don.

 

[dlightful zj]

You made mention of JU in your last reply. What is it? Where can I get a FSM?

 

[dondandd]

JU is the Jeeps Unlimited board (www.jeepsunlimited.com). It is probably one of the biggest and older Jeep boards, so it tends to have quite a bit of "history" that is worthwhile searching to see if your problem may have come up before.

You can definitly get your FSM from www.techauthority.com, but its worth checking the for sale sections of NAGCA, JU and such, or even Ebay to see if anyone happens to be selling a manual.

Don.