jimm

Heres what happened - 2004 strait 6 2wd Grand Cherokee Laredo

About 2 years ago my AC was very cold but I started to have issue, turns out it was the evaporator core which requires the dash and bend door unit to come out. When the job was done the AC was not ice cold like it use to be. The mechanic said the large blend door unit has insulation around it and it was not good, piece were coming off and allowing warm air from the heater core to mix in. He said I could bypass the heater core, I do live in south FL but it can get into the 40s during the winter and I have kids so I didnt want to do that. Another thing I notice after the job was I could smell the air outside like it was set to fresh air ie: if Im behind a bus I can smell its exhaust. Also, my A/C drain pug clogged a few times after the job with loose insulation, I had to unclog it to let the excess water out. The heater core was also replaced at the same time FWIW. A few months ago I had the compressor replace by the same mechanic, the clutch burned up. Nothing has changed as far as the cool, not real cold air.

$900 for the heater core /ac evaporator and $675 for the compressor and I have "cool" air

One thing I notice a few moths ago when driving during a cold snap with NO ac or heat on and I hope this helps to figure out what I can do about this. I started my jeep up and drove off one cold morning, my hand was on the shifter and I notice a slight cold breeze on my hand, it wasn't coming from the vents, it appears to be coming from somewhere underneath the
dashboard /clove box on the passenger side. Heres the kicker, as the jeep warmed up the air also became less cold, it eventually became like room temperature so outside air was coming in which was very cold, temp outside was in the mid 40s but that cold air became less cold as the jeep warmed up. So bypassing the heater core doesn't stop the outside air coming in, if its 90 outside that hot humid air will be coming in from underneath the dash on the passenger side

Let me add that before all of this started air in general never came out that good excerpt for one vent, the one to the left of the radio, that one blows hard

I just replace the blower and when I did I seen a blend door above it that appears to open and close when switch from max ac to regular but not sure how good it seals when closed

OK, I tried to get everything I could think of in, what do you think the issue is and what can I do to get the the air colder in my jeep? In notice outside temps play a role, if its in the 60s outside it blows much colder as apposed to the 80's

wingless

Welcome to the forum.

It sounds like the A/C guy didn't do a good job the the HVAC box.

When I did mine, I wasn't happy w/ the insulation on the doors, so I replaced that foam.

The problem(s) may be confined to improper air leakage. There might also be improper functionality of the refrigerant system. The refrigerant performance is measured using a manifold gauge set and thermometers.

There is not a way to quantify good / bad air leakage, that I am aware. Yours sounds bad to me.

If the performance is unacceptable then the only option is to repeat the job, this time replacing foam or doors, plus correcting any other issues identified.

When I did this on my ZJ I concluded that this was the worst repair task effort of everything I did when I rebuilt my entire Jeep.

jimm

Thanks for the reply. is there anything I can do to stop the outside air from coming in without ripping the dashboard out? I worked on cars mostly when I was younger but this task looked like it was gonna take a long time, I watch a youtube video and I could not commit to doing this job, thats why I had a mechanic do it

You mentioned improper functionality of the refrigerant system, how do I have this checked/tested?

4.3L XJ

You can do a quick check to see if it is charged close to right. Open the hood and let it run in that nice Florida humidity. All the metal parts on the return line should be dripping wet in just a very few minutes. If not, it is not charged correctly

jimm

OK thanks

97grand4.0

Um well this is AC service 101. What you need is to replace the accumulator/dryer, and the orifice tube / expansion valve , or the equivalent terminology of those two things. Then have a competent person pump a vacuum on the system, THEN refill with proper amount of refrigerant with UV dye, start it up and check for leaks.

If the dryer and orifice aren't replaced its a bad job there.

wingless

No need to add refrigerant.

Once the system has been evacuated w/ vacuum, shut the pump and valves, let is sit to determine if it holds the vacuum or if there are leaks.

97grand4.0

Absolutely. I was a bit foggy there.
Pump it down and see if it holds vacuum.

tom3holer

Just a thought but running the temp cold with the AC off and checking to see if warm air is coming out the vents tell how much, if any, air is leaking through the heater coil?

dave1123

I have the same problem with outside air leakage from under the dash and it's NOT coming from the heater vents. It seems to be worse when the radiator fan is running. I'm going to check around any thru-firewall opening like where the heater pipes or A/C pipes come thru. Even the radio antenna cable grommet. I've already checked the steering column boot.

jimm

I checked, the lines are cold and I do see some condensation but its not dripping off the lines. I dont now much about the dryer but one of the lines coming off the dryer seemed almost boiling hot

4.3L XJ

That line should be hot. Based on your description, I am going to say it is not charged correctly. If it was mine, I would be making sure it is charged correctly before trying to address the dash situation. You may find that if the evap coil gets colder, your AC is working properly

dave1123

The reason you should pump down the system is to remove all the air in it that could have moisture in it. That's what the drier is for, but it only can take so much. On older systems, it's a good idea to change it also. Moisture in the system can freeze in the expansion orifice and back pressure the compressor with liquid refrigerant and lock it up. Ask me how I know.

Peter1969

97grand4.0

expansion orifice valve, new accumulator dryer, vacuum down check for leaks, fill it up. If you skip any of those, you're never going to get factory cold. for one thing if you dont vacuum down and then add refrigerant, you can't get the proper amount of refrigerant in the system.

Newer systems also should get a new cabin air filter.