98 wrangler no heat or AC

440_D50 · Sep 18, 2010

My friend's heep is acting crazy. She says she has no heat and the AC will work for about 10 minutes, then start blowing luke warm air. She had a brand new heater core installed last year. Her blower motor is working. Is there something more to look at? Is there some sort of relays?

JOOP · Sep 18, 2010

If there is no heat, then she has an air bubble in the heater core or it's leaking. OR she has a coolant leak somewhere else. The AC is a different area, but probably has a leak and needs to be fixed and recharged.

Flat-Bed_3rd_Gen · Sep 19, 2010

for no heat it probably has an air bubble, for the a/c after it starts acting up does air-flow cut down? and if so does it do it on hot and cold?

440_D50 · Sep 19, 2010

I have not personally looked at the jeep yet, thats why im asking about relays or typical blend door problems. Looking for info on typical problems with these piles. Just found out some more info from her today.

First off, her brother replaced the heater core, and he's not really a mechanic. LOL.

According to her, the heat hasn't worked since the heater core replacement. I'm leaning towards an air pocket as well. Is there a way to bleed it? I little valve or something?

The air flow has been less since it's replacement as well. She says it used to blow harder on high. I'm gonna look at the blend door to see if it's opening all the way.

Apparently the AC works good for 10 minutes, then the air flow will slow down, speed up, just be erratic. It blows the room temp air, then goes back to cool after a while. I'm thinking the compressor clutch is acting up, but again, haven't looked at it yet.

Any helpful advise before I dive into this thing would be awesome.

JOOP · Sep 19, 2010

Pull the top heater hose from the thermostat housing and fill it with antifreeze from there. Then reconnect and run it for a while idling with the radiator cap off to burp out the air. Might help too if you prop the front end up.

Flat-Bed_3rd_Gen · Sep 20, 2010

so with the no heat thing, open the rad cap turn the heat on and rev the engine it will force the air out and you'll kn ow when it does its a real sudden temp change.

the a/c problem sounds like the evap core might be freezing solid which causes the air flow problem, i've seen it on a coupe of jeeps

pokey · Sep 20, 2010

Early tjs had a issue with the control panels. Since you are having issues with both the heat and AC I would be looking there first.

Fordzuki · Sep 21, 2010

It may sound stupid, but make sure the heater hoses are not reversed.

440_D50 · Sep 21, 2010

Ok, so i finally looked at it after work today in the parking lot. It blows ice cold air all the time. :rb: The blend doors seem to be working. :cheer: They are moving underneath the dash. it goes from defrost, to floor, to vents no problem. The fan blows faster out the vents when you put it to cold instead of hot.

The AC compressor is always cycling. Even with it on defrost and all the way to hot, it just keeps cycling under the hood.

Now for the strange part, and this is all while running. It runs at a steady 210 indicated. The top radiator hose gets super hot as it should, but neither heater core hose heats up. The top just barely, the lower ice cold. The top one has a little pressure release/fill valve inline. I opened it, pretty much nothing. I pulled the top hose off at the thermostat, nothing but fluid coming from the radiator, down the radiator hose, and out the heater core nipple of the thermostat housing.

I pulled the lower heater core hose near the front of the engine, again nothing. I waited a little and fluid started coming out of the hard line I pulled the hose off of.

I put it all back together, drove it around, no change on the temp gauge. Came back, opened the pressure/fill valve, nothing. Opened the radiator cap, pressure as it should:redneck:. I could not see any kind of flow from the upper hose into the radiator though. Seems the thermostat is completely stuck closed, or the water pump isn't working. But on the other hand, it isn't overheating or erratic temp at all. I'm gonna tear into it in my garage Friday. Wish me luck:haha:

ain'tstuckjustresting · Sep 21, 2010

Sounds like the flow control valve is stuck closed. Maybe he didn't hook it back up when he installed the heater core. Also, the a/c comp is supposed to cycle anytime the defrost is on. It helps dry the air to defog the window faster.