Need some A/C advice

jsalinas000

jsalinas000

New Member
Joined
Sep 2, 2020
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5
Location
Rosenberg, Texas
Hey there! I have a 97 Wrangler 4.0 Straight 6.
I am having issues with the AC, and can't figure out what it is. There is plenty of freon in the Jeep and the air blows hard, but fluctuates between cold as heck to hot as heck! You just never know what the AC is gonna do. Sometimes I will turn it off for awhile then turn it back on to get cold air. Could it be the evaporator? Compressor? Condenser? I like to work on my Jeep, hate paying a mechanic tons of money. Thanks, yall!
 
Sounds like the blend door might be doing something funky. The A/C won't produce heat in the cab, but the heater core always does. What could be happening is the blend door is moving and allowing air to blow through the heater core.

That could be an issue with the blend door actuator, an issue with the switch, or the wiring in between.
 
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Steel City 06 said:
Sounds like the blend door might be doing something funky. The A/C won't produce heat in the cab, but the heater core always does. What could be happening is the blend door is moving and allowing air to blow through the heater core.

That could be an issue with the blend door actuator, an issue with the switch, or the wiring in between.
Click to expand...
Is this something that can easily be fixed? How can I check the blend door? Thank you so much!
 
With the engine running and the AC turned off, look under the hood and you will see the AC pulley spinning but the "center" of the AC pulley will be stationary, the stationary part is called the AC clutch. Turn on the AC and you should hear a slight "click" and the AC clutch should now be turning, if it is then the AC is running. With the AC turned on and the AC clutch spinning the low pressure line and accumulator should be getting cold and since you are in south Texas they will start to condensate, that lets you know that the AC is working (as opposed to putting a set of gages on the system) and should be blowing cold air.
When you have the problem of the AC blowing hot when turned on you can check to see if the AC clutch is spinning and the lines are cold, if they are then you probably have a blend door problem like Steel City suggested.

The AC compressor is located on the passenger side of the engine compartment on top, follow the belt (don't touch it with engine running) it will have two large line coming from it, one of those lines will lead to the condenser (in front of the radiator) which is called the discharge line, the other will lead to the accumulator that is called the suction line. The suction line is the one that will become cold during operation. The accumulator is located just next to the battery in line with the suction line.

Google "Redneck Garage jeep TJ project AC install compressor crap" and that video shows where the parts are located.
 
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jsalinas000 said:
Is this something that can easily be fixed? How can I check the blend door? Thank you so much!
Click to expand...
The blend door itself is deep in the dash, and you typically have to pull the dash to get to it (very time consuming).

If the rest of the A/C system is working normally but you're getting heat occasionally, it could be the blend door. Check the compressor first like stated above.

You might look into the factory service manual and see if there are any instructions on how to diagnose a blend door actuator:
https://wranglertjforum.com/threads...ice-manuals-fsm-technical-documentation.4618/
 
I had this problem, there’s a connector under your power steering pump on top of the compressor, check that, you can loose the the PS pump and get to it to wiggle, also check your connections at the over charged and under charged sensors (located on top of that metal canister near your passenger footwell, where all the water drips, wiggle those and see if that fixes it.

those pressure sensors can be replaced without draining the system, they have a bicycle style tirevalve bung, so you just unscrew it and put a new one on, I went with cheapauto store replacements, cause if they fail the Jeep still drives and it was like less than20 for both orileys sensors, MOPAR wanted like 50 for 1 of them.
 
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It may very well be an issue with the refrigerant charge. When you say it has "plenty of freon" do you know for sure that it's charged to the correct weight? Our TJs don't take much, and AC systems need to be charged to a specific weight. Too little or too much refrigerant will trip the pressure sensor in the system and turn the compressor off to prevent damage. As the pressures equalize & return to normal levels the compressor will kick back on until the pressure sensor turns it off again. Have you had it evacuated & recharged with the correct weight of refrigerant?
 
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Steel City 06 said:
Sounds like the blend door might be doing something funky. The A/C won't produce heat in the cab, but the heater core always does. What could be happening is the blend door is moving and allowing air to blow through the heater core.

That could be an issue with the blend door actuator, an issue with the switch, or the wiring in between.
Click to expand...

When the temperature shifts from cooling to heating you should check the mode selector and the vacuum to it.
Either of these can cause the shifting that you are referencing.
 
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qslim said:
It may very well be an issue with the refrigerant charge. When you say it has "plenty of freon" do you know for sure that it's charged to the correct weight? Our TJs don't take much, and AC systems need to be charged to a specific weight. Too little or too much refrigerant will trip the pressure sensor in the system and turn the compressor off to prevent damage. As the pressures equalize & return to normal levels the compressor will kick back on until the pressure sensor turns it off again. Have you had it evacuated & recharged with the correct weight of refrigerant?
Click to expand...

Exactly... what I was typing when you posted.
The refrigerant charge is WEIGHED in and this can only be done after the system has been fully evacuated.
The evaporator coil can also frost up due to a low charge and in humid areas that is quite common when the charge is low.
 
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qslim said:
It may very well be an issue with the refrigerant charge. When you say it has "plenty of freon" do you know for sure that it's charged to the correct weight? Our TJs don't take much, and AC systems need to be charged to a specific weight. Too little or too much refrigerant will trip the pressure sensor in the system and turn the compressor off to prevent damage. As the pressures equalize & return to normal levels the compressor will kick back on until the pressure sensor turns it off again. Have you had it evacuated & recharged with the correct weight of refrigerant?
Click to expand...
Can you tell me how much freon it takes? If the compressor is off bc of the sensor, would it still blow cold? I get intermittent cold and hot, mostly cold but it the air gets warm occasionally.
 
jsalinas000 said:
Can you tell me how much freon it takes? If the compressor is off bc of the sensor, would it still blow cold? I get intermittent cold and hot, mostly cold but it the air gets warm occasionally.
Click to expand...
Is it warm like outside warm? If so, it's probably a compressor issue rather than blend door issue.

You'll need a kit to measure pressure as you add refrigerant to get it within a target range. Ideally, you measure both high pressure and low pressure simultaneously, but you can often get away with low pressure only. The kits sold at every auto parts store measure low pressure only.
 
qslim said:
It may very well be an issue with the refrigerant charge. When you say it has "plenty of freon" do you know for sure that it's charged to the correct weight? Our TJs don't take much, and AC systems need to be charged to a specific weight. Too little or too much refrigerant will trip the pressure sensor in the system and turn the compressor off to prevent damage. As the pressures equalize & return to normal levels the compressor will kick back on until the pressure sensor turns it off again. Have you had it evacuated & recharged with the correct weight of refrigerant?
Click to expand...
+1 Check Freon levels first.
Also make sure the service ports have caps and there are orings installed in them. The schrader valves are known to weep. You can buy the caps at Oreilles for a couple of dollars.
 
Steel City 06 said:
Is it warm like outside warm? If so, it's probably a compressor issue rather than blend door issue.

You'll need a kit to measure pressure as you add refrigerant to get it within a target range. Ideally, you measure both high pressure and low pressure simultaneously, but you can often get away with low pressure only. The kits sold at every auto parts store measure low pressure only.
Click to expand...
that's what I use - the kit with the gauge from Oreilly. That gauge says it is full
 
jsalinas000 said:
that's what I use - the kit with the gauge from Oreilly. That gauge says it is full
Click to expand...

Full? You really need to see what the pressures/temp is and for that you need an actual A/C manifold set. You can rent the manifold set thru Oreilles.
 
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