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Discussion Starter · #1 ·
Howdy,
I have a 2007 Jeep SRT8 and I'm having A/C issues and I'm trying to find out where the evap temperature sensor is located on my jeep, normally I'd just start taking everything apart until I found it but the jeep is a real pain so I'm hoping someone here knows the location and if there is an easy way to change the sensor out.
Thanks for your help
 

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. . . I have a 2007 Jeep SRT8 and I'm having A/C issues and I'm trying to find out where the evap temperature sensor is located on my jeep, . . . .
Here is an exploded image of the HVAC components in a 2007 Jeep Grand Cherokee. If you have a center console you may have to work around it or remove to gain access.

Text Auto part Diagram


What particular problem / issue are you having with the A C system?
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Welcome to Allpar. You might want to read what actual temperature the probe is seeing with a good scan tool before trying to replace it. It may be accessible behind the glovebox?
The ATC module may also have useful stored fault codes. These can't be read with a basic OBDII engine code reader. There were a couple of TSBs for A/C issues:
http://www.wkjeeps.com/TSB/tsb_wk_2400207a.pdf
http://www.wkjeeps.com/TSB/tsb_wk_2400209a.pdf
If you are planning on DIY, find yourself a factory service manual.
 

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Discussion Starter · #4 ·
Here is an exploded image of the HVAC components in a 2007 Jeep Grand Cherokee. If you have a center console you may have to work around it or remove to gain access.

View attachment 24455

What particular problem / issue are you having with the A C system?
A/C works when i first turn it on but compressor stops engaging after 15 minutes or so, i had the system vacuumed and refilled and replaced the pressure switch and the expansion valve and tested fan speed, the weird thing is if im going about 70mph and floor it until i hit 7k rpm and 115mph the a/c starts working again but if i just roll up to 155mph it wont kick back on.
 

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I would suspect a leak, and check the pressures again. Revving the engine high enough, might just create enough pressure in a nearly-empty system to overcome the low-pressure cutoff switch.
Why was it serviced before with the expansion valve and pressure switch? What symptoms prompted that repair?
 

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Discussion Starter · #6 ·
the system was over charged when i bought the jeep and acting up so a friend of mine who does hvac professionally hooked up a bunch of gauges and said the expansion valve was bad so he replaced it as well as the switch and did some vacuum thing on it then charged it up and but the compressor would stop engaging after about 15 minutes of usage still and i havent had a chance to talk about it again so i just started looking up on the internet on what else would make the compressor shut down like that and the evap temp sensor war next on the list, i have had the system checked for low freon 3 times since then and it has always been in the green on the gauge. the ac doesnt always work after high rpm but sometimes does and usually will work again after the jeep is shut off for a few minutes, im just trying to figure this out so i dont have to bug my buddy about it but i am a/c tarded.
 

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. . . i have had the system checked for low freon 3 times since then and it has always been in the green on the gauge. the ac doesnt always work after high rpm but sometimes does and usually will work again after the jeep is shut off for a few minutes, im just trying to figure this out so i dont have to bug my buddy about it but i am a/c tarded.. . . .
This sounds like some restriction in the system that is causing the discharge side to over pressure. The PCM receives constant data about the discharge side system pressure. If it exceeds approximately 450 psi then the compressor clutch will disengage. It will take several minutes for the over pressure to subside and then the PCM will allow the compressor clutch to be engaged again.

Do this test in full sunlight, windows raised and closed to put high heat load in the cabin and on the A C system. Pressure gauges should be connected to the suction and discharge sides of the system. Engage the compressor and watch the discharge pressure as you raised the engine rpm to 3,000 - 4,000 rpm. You should not exceed 400 psi discharge pressure under extreme heat while the suction side should be 25 - 35 psi.

When the system stops cooling is air flow reduced from the vent outlets? If this is happening then it is possible that the evaporator is icing and restricting cooling. This would be an indication that the evaporator temperature sensor is not functioning properly.
 

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Discussion Starter · #11 ·
This sounds like some restriction in the system that is causing the discharge side to over pressure. The PCM receives constant data about the discharge side system pressure. If it exceeds approximately 450 psi then the compressor clutch will disengage. It will take several minutes for the over pressure to subside and then the PCM will allow the compressor clutch to be engaged again.

Do this test in full sunlight, windows raised and closed to put high heat load in the cabin and on the A C system. Pressure gauges should be connected to the suction and discharge sides of the system. Engage the compressor and watch the discharge pressure as you raised the engine rpm to 3,000 - 4,000 rpm. You should not exceed 400 psi discharge pressure under extreme heat while the suction side should be 25 - 35 psi.

When the system stops cooling is air flow reduced from the vent outlets? If this is happening then it is possible that the evaporator is icing and restricting cooling. This would be an indication that the evaporator temperature sensor is not functioning properly.
Any ideas?
 

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. . . i hooked up a gauge setup and when ac clutch stops engaging the gauge marked low reads 125psi and the gauge marked hi is only reading 140psi. . . .
I wonder if the system is still overcharged with refrigerant? At rest and when the A C system has not been used for several hours, the suction and discharge sides of the system reach equilibrium. With a properly charged system and summer time temperatures of 80 - 90 deg F, I would expect system pressure to be about 85 - 90 psi. The 125 psi on the low side is too high and hints of a refrigerant overcharge.

If the discharge pressure can only reach 140 psi with the suction pressure relatively high, that indicates a mechanical problem with the compressor.
 

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Discussion Starter · #13 ·
I wonder if the system is still overcharged with refrigerant? At rest and when the A C system has not been used for several hours, the suction and discharge sides of the system reach equilibrium. With a properly charged system and summer time temperatures of 80 - 90 deg F, I would expect system pressure to be about 85 - 90 psi. The 125 psi on the low side is too high and hints of a refrigerant overcharge.

If the discharge pressure can only reach 140 psi with the suction pressure relatively high, that indicates a mechanical problem with the compressor.
Sounds like i need a new compressor.
Thanks for your help!!!
 

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. . . Sounds like i need a new compressor . . . .
If you have the A C compressor replaced make sure the old compressor is inspected for debris such as metal shavings. Hopefully nothing will appear but you do need to check.

Make sure the new, replacement compressor has the correct amount of lubricating oil. Some will be shipped with full oil charge and some will be dry. Drain and measure amount of oil in old compressor. If new compressor is shipped dry, add this exact amount of oil. If new compressor has full oil supply it needs to be drained and then the quantity drained from old compressor noted and new unit should be filled with new oil in this noted quantity.
 

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Had to wait until the ac would kick on but 40 on low pressure side and still 150 on high pressure side no change in air flow volume.
I would think this is undercharged, except that with compressor off, pressures of 125 to 140 do not indicate an undercharge, at least to me. So maybe the compressor is damaged.
One mistake some people make when charging is to invert the can of freon. This slugs the compressor with a wave of liquid refrigerant that cam damage the vanes. It must always be recharged with the freon canister upright. I've had people ridicule me for it, but this is the manufacturer's and the automaker's warnings.
 
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You can usually hear when a compressor sucks in a slug of oil or liquid refrigerant. Liquids don't compress. The noise is unmistakable and very sad. :(
The compressor may be OK if it is quiet. I wouldn't condemn it just yet.
The pressures are wrong. If it was charged with air instead of refrigerant, the numbers could look like this. Many shop recharging stations will charge with air instead of refrigerant as the tank gets empty.
Sometimes that can be fixed simply by evacuating and recharging the system with 100% pure refrigerant without having to open the system.
Too much refrigerant oil in the system can be almost as bad as too little refrigerant oil. It can foam, load the compressor and have a hard time squeezing through the expansion (or H-) valve.
Auto parts stores market a large array of 'miracle' products for A/C all claiming all kinds of things. Stop leaks are a Hail Mary repair and can cause more issues by gumming up the works without fixing the leak. They can also damage the shop's A/C reclaiming/recycling equipment.
Be sure to use OEM recommended materials and procedures for the best results. Wear eye protection.
 
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