Stumped on HVAC

***I know this is lengthy, but if you have time, sit down and read all of it. I made it as thorough as I could, with pictures, in hopes that it can easily be understood***

I recently bought a '95, 4.0l HO AW4, completely stock. This is a new introduction to me as far as Jeeps go, I've been into cars all of my life so I'm still learning about Jeeps. I am pretty mechanically inclined so I'm not completely clueless as far as that goes. Before anyone tells me to search, I have, that's how I knew to check the following items that are bold/underlined. I feel like this is a special case, that's the only reason I made a new thread for it.

Blower motor/Blower motor resistor/Heater control valve
I got it from a friend of mine (this is owner #2), and he had bought it from another friend of his (this is owner #1). The reason I said that, is because the 1st owner of the three of us, had said the hvac didn't work, and told the 2nd owner of the three of us that it just needed a blower motor resistor to fix it. Owner #2 that I bought it from, never bothered putting a new resistor in it, didn't mess with it at all the entire time he owned it. So. I got both a new blower motor resistor and blower motor and installed them at the same time. Still nothing. I looked at the little heater valve under the hood that runs to the heater core hoses, it tested as good.
So far we have the following things as being known as good:
-blower motor resistor
-blower motor
-heater control valve

Blower speed switch-?
A few nights ago I took the cluster trim piece off, the radio out, and unscrewed the climate control assembly from the dash and pulled it out a little bit (everything still connected as far as cable/wiring harnesses go) to see what I could find. I found this:





This is the harness going to the blower speed switch. Burnt up, ugly. I fixed the wire earlier (cut out burnt end, replaced section with new wire and soldered the connection, did it the correct way). I dissasembled the switch and found that the little rivet that goes through the plastic backing piece that holds the male end connector for that wire had burnt through the plastic, decided to get crafty and jb welded the rivet back to the plastic (parts stores are closed at 8pm on a Sunday around here, did the best I could with it.) Plugged everything back up, still nothing. Maybe the switch is bad? Everything should have been okay with how I fixed it, and put it back together just like it came apart. Maybe the switch is still bad? I'll let someone with more experience on here make that call.

Vacuum canister (behind front bumper)
Decided since that didn't do anything, that I would hop underneath the front bumper and check out the vacuum canister, as I had read that can cause problems too with vacuum leaks and only having the defrost vent work. It was basically sitting in there, with a vacuum line that was disconnect. Pulled the canister out, plugged that vacuum line into the vacuum T located on top of the passenger side fender well. Still nothing. The canister has no cracks or leaks.

-------------------------------------------------------------------------
A few days ago after I had first noticed the burnt wire going to the blower speed switch, I got home, pulled in the driveway and realized that the backlight for the climate control switch assembly (where you choose hot/cold and where you want the air to come out at) was lit up! Since I bought the Jeep I just thought the bulb was burnt out or something, because it didn't work until this occassion. I still had the radio out at this point, so I could see the harnesses going to the climate control assembly. Since the light was lit up, I figured eh, I'll wiggle the harness going to the blower speed switch and turn the switch to see if I could get anything. The heat came on for a few seconds, then I stopped wiggling the harness and it went off again.

Fuses
As of now, I have no backlight lit up, no heat/air. Before anyone asks, I did check the fuses before I began any of this process, however I'm a little puzzled on that also. I have a Haynes manual that I looked at, and it has 2 or 3 different diagrams for the kickpanel fusebox. On one diagram, I'll have some fuses that are correct, some that are not. On the next diagram, same story. Basically I cannot tell which spot in the fusebox is my blower fuse. I know that sounds dumb, but its basically like my kickpanel fusebox has been fused between two different diagrams.
***From what I understand, fuse #3 is supposed to be a 25amp blower fuse, is this correct? Because the #3 fuse holder is made to where I can't put a fuse in it for some reason? It has both pinouts for a fuse, but the actual plastic fusebox piece is raised up in the middle to where I cannot insert a fuse in that spot. Here is a picture of the box on MY specific Jeep:




See where the #3 location is? There's a power accessory spot that has the two pinouts, however has the raised up piece I was talking about. #3 looks like it has a pinout on one side, but not the other? Therefore I'm kind of lost as to seeing if the fuse is correct/in the correct spot, because of the two diagrams in my manual seemed to blended together, thus what I have. Any insight on this? I checked all of the fuses in the fusebox, and they were all fine. This still doesn't explain why the backlight worked and the heat did come on when I wiggled the harness, it would mean it had to have the fuse in it, but I can't tell what exactly is going on until I know for certain what each spot in the fusebox is for, and what size fuse goes where. This would be alot easier if my fuseblock matched up with either diagram in my manual.


I'm honestly not sure at this point. Should I try putting a NEW blower speed switch in to see if that does it? I know I sort of rigged it earlier, but I was doing the best I could do for a Sunday night. I would atleast think even if there was no air, the backlight would atleast light up. Does anyone have any input on this? I'm sincerely lost and out of ideas, other than possibly the switch. And I definately would like to get this fusebox situation figured out, I don't like not knowing what's what down there.

Anyone with any insight on this, please, speak up, it would be greatly appreciated. Thanks in advance,

Mike

Blower switch scarred like that needs to be replaced. I had the same problem and a junkyard switch fixed it.

Pull the vacuum line off the ball again and see if it is holding vacuum. You should hear a distinct hiss even a day after the car was last shut off. If not check for vacuum leaks all through the circuit.

HTH
Todd

WNC95xj said:

***I know this is lengthy, but if you have time, sit down and read all of it. I made it as thorough as I could, with pictures, in hopes that it can easily be understood***

I recently bought a '95, 4.0l HO AW4, completely stock. This is a new introduction to me as far as Jeeps go, I've been into cars all of my life so I'm still learning about Jeeps. I am pretty mechanically inclined so I'm not completely clueless as far as that goes. Before anyone tells me to search, I have, that's how I knew to check the following items that are bold/underlined. I feel like this is a special case, that's the only reason I made a new thread for it.

Blower motor/Blower motor resistor/Heater control valve
I got it from a friend of mine (this is owner #2), and he had bought it from another friend of his (this is owner #1). The reason I said that, is because the 1st owner of the three of us, had said the hvac didn't work, and told the 2nd owner of the three of us that it just needed a blower motor resistor to fix it. Owner #2 that I bought it from, never bothered putting a new resistor in it, didn't mess with it at all the entire time he owned it. So. I got both a new blower motor resistor and blower motor and installed them at the same time. Still nothing. I looked at the little heater valve under the hood that runs to the heater core hoses, it tested as good.
So far we have the following things as being known as good:
-blower motor resistor
-blower motor
-heater control valve

Blower speed switch-?
A few nights ago I took the cluster trim piece off, the radio out, and unscrewed the climate control assembly from the dash and pulled it out a little bit (everything still connected as far as cable/wiring harnesses go) to see what I could find. I found this:

This is the harness going to the blower speed switch. Burnt up, ugly. I fixed the wire earlier (cut out burnt end, replaced section with new wire and soldered the connection, did it the correct way). I dissasembled the switch and found that the little rivet that goes through the plastic backing piece that holds the male end connector for that wire had burnt through the plastic, decided to get crafty and jb welded the rivet back to the plastic (parts stores are closed at 8pm on a Sunday around here, did the best I could with it.) Plugged everything back up, still nothing. Maybe the switch is bad? Everything should have been okay with how I fixed it, and put it back together just like it came apart. Maybe the switch is still bad? I'll let someone with more experience on here make that call.

Vacuum canister (behind front bumper)
Decided since that didn't do anything, that I would hop underneath the front bumper and check out the vacuum canister, as I had read that can cause problems too with vacuum leaks and only having the defrost vent work. It was basically sitting in there, with a vacuum line that was disconnect. Pulled the canister out, plugged that vacuum line into the vacuum T located on top of the passenger side fender well. Still nothing. The canister has no cracks or leaks.

-------------------------------------------------------------------------
A few days ago after I had first noticed the burnt wire going to the blower speed switch, I got home, pulled in the driveway and realized that the backlight for the climate control switch assembly (where you choose hot/cold and where you want the air to come out at) was lit up! Since I bought the Jeep I just thought the bulb was burnt out or something, because it didn't work until this occassion. I still had the radio out at this point, so I could see the harnesses going to the climate control assembly. Since the light was lit up, I figured eh, I'll wiggle the harness going to the blower speed switch and turn the switch to see if I could get anything. The heat came on for a few seconds, then I stopped wiggling the harness and it went off again.

Fuses
As of now, I have no backlight lit up, no heat/air. Before anyone asks, I did check the fuses before I began any of this process, however I'm a little puzzled on that also. I have a Haynes manual that I looked at, and it has 2 or 3 different diagrams for the kickpanel fusebox. On one diagram, I'll have some fuses that are correct, some that are not. On the next diagram, same story. Basically I cannot tell which spot in the fusebox is my blower fuse. I know that sounds dumb, but its basically like my kickpanel fusebox has been fused between two different diagrams.
***From what I understand, fuse #3 is supposed to be a 25amp blower fuse, is this correct? Because the #3 fuse holder is made to where I can't put a fuse in it for some reason? It has both pinouts for a fuse, but the actual plastic fusebox piece is raised up in the middle to where I cannot insert a fuse in that spot. Here is a picture of the box on MY specific Jeep:

See where the #3 location is? There's a power accessory spot that has the two pinouts, however has the raised up piece I was talking about. #3 looks like it has a pinout on one side, but not the other? Therefore I'm kind of lost as to seeing if the fuse is correct/in the correct spot, because of the two diagrams in my manual seemed to blended together, thus what I have. Any insight on this? I checked all of the fuses in the fusebox, and they were all fine. This still doesn't explain why the backlight worked and the heat did come on when I wiggled the harness, it would mean it had to have the fuse in it, but I can't tell what exactly is going on until I know for certain what each spot in the fusebox is for, and what size fuse goes where. This would be alot easier if my fuseblock matched up with either diagram in my manual.


I'm honestly not sure at this point. Should I try putting a NEW blower speed switch in to see if that does it? I know I sort of rigged it earlier, but I was doing the best I could do for a Sunday night. I would atleast think even if there was no air, the backlight would atleast light up. Does anyone have any input on this? I'm sincerely lost and out of ideas, other than possibly the switch. And I definately would like to get this fusebox situation figured out, I don't like not knowing what's what down there.

Anyone with any insight on this, please, speak up, it would be greatly appreciated. Thanks in advance,

Mike

Click to expand...

I did hear little bit of a hiss, I might have a small leak somewhere in one of the vacuum lines, it didn't sound like it had alot of vacuum but there was definately some there. I work at Carquest right now so I'll get ahold of a new switch hopefully tomorrow and report back tomorrow evening with what I can find. Thanks for the quick reply Todd!

Mike

Update:

Got the switch in earlier, nothing happened. :/ I was aggravated, then when I was on my way home from work at a redlight I wiggled the harness on the right side of the climate control unit, then the lighting came on. I can hear a little bit of air moving up through the center defrost vent behind where the radio sits, but nothing. Even once the climate control backlight came on, nothing else. Wonder if that ground wire damaged both my blower switch and the climate control assembly also? I'm starting to think that's the problem, since the blower switch has been replaced and the wire was repaired/I wiggled the harness that goes to the CC assy and the lighting came on.. Any more ideas? That's all I can think of for now.

Mike

can you summarize what problem(s) are you having? you are listing all the things you've done but I can't figure out what you are trying to fix

True point, I just realized that haha. I got the Jeep with no working air or heat, nothing at all from the vents. Basically, I'm trying to figure this out before it starts getting cold here (we had a pretty ferocious winter last year in the mountains of NC). I replaced the blower speed/fan speed whatever its technical name is switch yesterday, I have a little bit of air coming through the defrost now but thats it. My backlighting on the climate control assembly still doesn't work, last night I wiggled the harness for it (the long skinny one that plugs in on the right side behind the climate control) and the backlight came on, but still no heat/selection of where air goes etc. I'm starting to think that's my culprit, is the climate control assembly itself. Thoughts/opinions? I'm really not sure how to put a volt meter to it and test it, is there a way to do this? I feel like I'm getting really close to figuring this out, I'm running out of things that could be bad anyhow.

Mike

One of the 25 amp or 30 amp fuses should be the AC/Heat blower power fuse. It may also run the windshield wipers if wired the same as the Renix jeeps, 85-90 were wired. My 87 also had the radio, the electric windows and electric door locks and elctric seats all on the same tiny 12-14 gauge wire!

The Renix jeeps were bad about overloading that wire all the way from the fuse panel to the ignition switch to the Fan switch. I burned out 2 ignition switches running the blow on max for just 3 months!

So I suggest checking the electrical ignition switch (not the key mechanism), which is way up under the dash on the steering column, operated a 12-18 inch long rod that is connected to the lock mechanism of the ignition switch.

I have replaced the fused wire at the fuse box on my 85, the fuse assy with a single separate one, in line, and on the 87 a new ignition switch, a 30 amp dash toggle switch bypass of the ignition switch, a new fan switch, and new resistor pack, new motor and repaired or replaced all the damaged wire with 10 Gauge wire, and never had any more problems (been a good 5 years now). ON the 85 I just hot wired it to the battery with a single full speed 30 amp switch at the battery (LOL) after giving up on all the old wiring in the 85.

Was driving home from work this evening, looked down, saw the lights on and the heat worked, directions worked as well. I think it's something somewhere in the wiring harness because when I pushed back on the assembly like how it would be screwed in, it cut out, then back on again. Who knows.

Update:

After driving the Jeep the last few days, I've noticed that my climate control assembly won't light up/function at all for awhile, then when I get going down the road (at full operating temp?) it will start working, and I have heat. However, after a new blower fan speed switch, the highest setting it will perform *the best* is at level 3, not 4. Level 1,2, and 4 feel about the same. Anyone that has many years experience with XJ's under their belt have any input? I really have no clue what it could be at this point.

Bump:

I still have no backlight for the hvac control assembly, and none of the settings work except for the vent setting (will blow some warm air out once at full operating temp, thats about it.)
Ideas anyone?

WNC95xj said:

Update:

After driving the Jeep the last few days, I've noticed that my climate control assembly won't light up/function at all for awhile, then when I get going down the road (at full operating temp?) it will start working, and I have heat. However, after a new blower fan speed switch, the highest setting it will perform *the best* is at level 3, not 4. Level 1,2, and 4 feel about the same. Anyone that has many years experience with XJ's under their belt have any input? I really have no clue what it could be at this point.

Click to expand...

There is a cheap resistor pack that has 4 resistors that work with the fan switch to give the different fan speeds. They get wet, rust and burn out over the years. It is under the dash, on the face of the big black box that holds the evaporator-heater core and damper doors assy, passenger side. Two little screws hold it on, and it has a 4 or 5 wire plug attached to it. Real easy to find. May be a dealer only part. About $5 - $10.

I've replaced the blower motor resistor if thats what you mean, also at the same time as the blower motor itself.. I've basically replaced everything that could electronically fail minus the actual assembly, which I'm hoping it isn't because no junkyards around here have one. I'm about to be done with it and buy the first one I find and try it, I honestly think thats the problem at this point. I'm just trying to see if theres anything else it could be before I do that.

I have three working (now), 85, 87 and 89 Renix jeeps, and other than the vacuum lines coming loose while working around the controller, It is one of the few parts I never had to replace. But yours is a newer year.

In addition to what you have done, I have had to bypass the fuse box on my 85 and 87, with new wires and inline fuses. Yours looks clean and new like my 89, so that leaves just the wire at the ignition switch and ignition switch that feeds the blower motor and speed switch, which I have had to replace or repair the wire and the ignition switch on ALL three to fix the last of the blower motor running issues on mine.

I also had vacuum issues under the hood on all three, and a bad damper door valve (vacuum operated) on the 85. All the vacuum lines must all be perfect seals or the fan speed changes when you hit the gas peddle, LOL:laugh3:!