A/C all of a sudden blows HOT!!!

Hey gang,

My 2001's A/C all of a sudden turned into a heater! It seems as if whatever valve is operated by adjusting the thermostat is stuck on "hot" (where I normally have it). I crank down the temp to cold, and it just blows heated (HOT!!!) air.

Any idea what part I need to replace, what is costs, and how to replace it?! If you can help, let me know!

Also, one other thing I noticed. I think my A/C might have a leak now...it's strange. If I engage the A/C compressor (and you can hear it kick on), then shut off the car...there's a "hissing" sound like leaking gas for about 3 seconds coming from the passenger side of the engine. Sounds like it might be one of the steel A/C lines that passes through the firewall.

If I go to an A/C shop, are they going to rob me blind? I'd love to fix it myself, but I'm not quite sure how. Let me know! Thanks!!! :loveu:

Sounds like the blend door is getting stuck. I believe its operated by a cable that runs from the climate control panel to the clip sticking out the side of the heater box. Look in the passenger area, near footwell..

When my 01 started blowing hot on A/C it turned out to be a refrigerant leak...I had it serviced under warranty...first attempt by the Dealer was to recharge with new refrigerant loaded with a visible dye. A/c blew cold for a day and then leaked out again. The dye showed that the leak was from the evaporator. Dealer told me this is a very common point of failure on the 01 Jeep and several other model years. The replaced the evaporator and recharged the system...everything has been fine for the last 2 years now.
If I did not have extended warranty this would have been a very expensive repair...$800 plus.
So...having said all that, you will need to determine if your refrigerant charge is up to the appropriate pressure level...if not, the low pressure sensor will not allow the compressor to engage. If you do not have the specialty tools needed, and knowledge on how to use them, to evacuate the old refrigerant, find the leak, replace and repair the bad component, and then recharge the system, you are at the mercy of a shop that can do it.
I do know that you can buy a refrigerant recharge bottle at the auto parts store, that will have instructions on how to use it, if your A/C system simply needs a charge because it has a slow leak that has finally dropped pressure below startup spec., but that is a long shot it will be a permanent fix.
Personally, I would spend some quality time looking for an A/C repair shop that comes highly recommended by someone you trust.

Good luck with it...hope that helps....
McQue

What if it also blows hot (no matter what the temp dial reads) on FAN, without the A/C engaged?

xL8 APEKSx said:

What if it also blows hot (no matter what the temp dial reads) on FAN, without the A/C engaged?

Click to expand...

from my FSM

TEMPERATURE CONTROL​

If the heater outlet air temperature cannot be
adjusted with the temperature control knob on the
A/C Heater control panel, the following could require
service:​

†​

​

†​

​

†​

​

† Improper engine coolant temperature.

If the compressor kicks on, refrig is fine. I'll see what I can find about the cable. It's almost surely that or the blend door.

You guys rock, now I just need to know how to access said blend door.

xL8 APEKSx said:

Also, one other thing I noticed. I think my A/C might have a leak now...it's strange. If I engage the A/C compressor (and you can hear it kick on), then shut off the car...there's a "hissing" sound like leaking gas for about 3 seconds coming from the passenger side of the engine. Sounds like it might be one of the steel A/C lines that passes through the firewall.

Click to expand...

Completely normal. Just the AC system de-pressurizing when you shut it off. Nothing to worry about there

HELP PLEASE!!
i now have this exact problem. i have done some searching for blend air/cable hook up but cannot find it. when the a/c is on, nothing but heat is coming out of vents. under the hood the ac lines are cold. and pep boys guage says freon is on the money. so i believe it is somewhere behind the glove box.
any ideas???

On my year model (92), the blend door cable as is the blend door is on the passenger side of the vehicle. As stated above it connects the temp control to the blend door. If you look under the dash on the passenger side, you should see it.......and it will hook to a lever that operates the blend door.

Not sure of the exact path, but on mine, it came from the front top of the evaporator housing to the bottom just on the tranny hump side of the passenger compartment.....held there by a small clip.

I thought I had the same problem with the blend door, but i have a '98 and I found the cable to be working fine and it looks to be moving the door back and forth.

The tube running into my evaporator is cold (moisture condensing on the outside of it), and the compressor starts up 2-3 times per minute.
when i change the knob to heat, it comes out perfectly hot.
when I change to cold, I just get 'ambient' air temperature out the vents.

never any cold air.

any thoughts ?

crossmax03....in addition to my 92, my kids have a 2001. On the 01, I found that someone had put a on/off valve in the heater line that comes back to the heater core. If the valve was open in the summer, you could hardly tell the AC was on....it would be pretty warm. Cut the hot water flow and the AC works great.

If your problem came about suddenly, I doubt that is your problem.

On a sudden loss of cool air from the a/c, make SURE the blend door is closing off properly, if it mixes any air...you will lose cooling power.

xray1971 said:

http://www.heatertreater.net/

Click to expand...

Boy, was I glad to get this link! I have both a CTD Ram and a 2001 XJ Limited. Will be using the max amount of "kit" to fix both against any future problems.

xray1971 said:

http://www.heatertreater.net/

Click to expand...

Boy, was I glad to get this link! I have both a CTD Ram and a 2001 XJ Limited. Will be using the max amount of "kit" to fix both against any future problems.

(And am thinking of installing shut-off valves -- with bypasses -- for the heater core. Eight months, minimum of A/C use here in South Texas; and it is a product we installed on Class 8 trucks to keep them bearable. Guess I'll use Bill Plocks' guide to installing coolant bypass filters as well [do search]).