Gen 3 A/C issues

[spacecowboy7777]

Morning all, I'm having an A/C issue. Last summer, my A/C started intermittently blowing warm. It happens really consistently now, it will usually start off cold, then go warm after 10-20 mins of cold. It happens quicker if outside ambient temp is high or dry. I brought it in to the shop, they evacuated and refilled A/C , but the problem continued. They told me that I need a new AC pressure sensor and a new AC condenser, but at $1,000 total, I passed on them performing the work. Does this sound possible to you all? I have the parts and can install myself, but I don't want to pay $200 for another recharge if it does nothing.

I have looked around the radiator and condenser and I see no obvious airflow problems or debris.

How difficult is it to replace that condenser?

Another abnormal thing is the AC condenser fan stays on even after I turn the AC off. It will usually stay on until I park the car. Does this sound like the sensor and/or condenser? All suggestions are appreciated.

I guess my main question is, does a condenser just go bad? Vehicle has 170,000 miles on it. Makes sense that a switch or sensor can fail, but I'm curious about the condenser.

2002 montero limited

 

[Michael Brown]

I'm sure anything can go bad at some point, but there's several vehicles with 200k miles and working AC.
It is odd that it starts cold then gets warm.

I would check the engine coolant level in the radiator to make sure it isn't getting low and possibly overheating the system through the heater core.

A recharge can be done with one of the cans at the auto store and the provided gauge tool. The system has ports to connect it.
The fan is likely controlled by a temp sensor in the condenser.

Maybe there's something in the FSM that can help with troubleshooting.
If this is a limited model, you can check function of the rear AC as well. It has its own condenser and blower assembly in the rear.

 

[spacecowboy7777]

I'm sure anything can go bad at some point, but there's several vehicles with 200k miles and working AC.
It is odd that it starts cold then gets warm.

I would check the engine coolant level in the radiator to make sure it isn't getting low and possibly overheating the system through the heater core.

A recharge can be done with one of the cans at the auto store and the provided gauge tool. The system has ports to connect it.
The fan is likely controlled by a temp sensor in the condenser.

Maybe there's something in the FSM that can help with troubleshooting.
If this is a limited model, you can check function of the rear AC as well. It has its own condenser and blower assembly in the rear.

Thank you for the reply. I went looking for a temp or pressure sensor by the condenser and found the pressure sensor that the shop said is probably bad. I think it's just a simple cut off switch if the pressure gets too high. With the truck completely cold, not driven in a day, I unplugged the sensor and tested it for resistance. It read as having little to no resistance. I THINK that means either there is too much pressure in the system, even after not being used or driven for a day, or the sensor is bad. Next step for me is to try driving it around and testing the ac with that sensor unplugged.

 

[spacecowboy7777]

Well, it looks like I was wrong. The factory service manual states that switch should have continuity when everything is normal. And it loses continuity if pressure falls or increases to a bad pressure. So I think right now, the reading is good.



So the switch still could be the problem. But for now, it is reading correctly. I'll try to jumper the connector to see if that makes the ac blow cold consistently.

 

[spacecowboy7777]

Update: that sensor checks out. I idled the truck for a while with the AC on. It was cold as ice for 5-10 minutes, but eventually became warm as expected. It sounded like the compressor was no longer kicking on. The switch measured as normal and once the ac became warm, unplugging the switch had no affect. While the ac was working, plugging and unplugging the switch turned the ac compressor on and off.

Next in the factory manual, it says:




I cannot find a part number for this thing. Anyone know where or what it's talking about?

 

[Michael Brown]

Does your vehicle have the automatic AC controls? My 05 Limited has an auto AC setting which will control the temperature of the air to reach a set temperature like a thermostat in the house. It doesn't just control fan speed.

That could be the controller the FSM mentions. That also would be why your AC changes temp. Once the in car sensor reaches the desired temp, it levels off to maintain it.

Changing from Auto will keep it at the same air outlet temperature. Check that next.

 

[spacecowboy7777]

Thank you all for the help. I did try changing to auto and same problem. I ended up having the shop replace the condenser and the switch based on their recommendation but it did not fix the problem. They said the condenser was leaking, but idk how true that was, but it’s possible. Regardless, my problem continued.

SOLUTION: my cooling system had air in it. So the ecu temp sensor was reading around 240* and thought my car was overheating. When our cars overheat, the ecu turns off the AC compressor as a safety feature. Apparently there are two temp sensors for our cars, one that the ecu reads and one for the dash gauge, so the ecu was reading high while my dash gauge never left normal range, which is why I never noticed. After correctly bleeding the cooling system to remove all the air, along with the new condenser and fresh charge, my ac works incredibly well, even sitting in stop and go traffic through the concrete summer oven of east LA for a couple hours at a time.

You can check what temp the ecu is getting by connecting a scan tool to the obd2 port.

I’m thinking I didn’t really need the condenser and could have saved $800, but it’s too late now and I’ll never know for sure. I’m just glad my ac works and I hope this helps someone in the future.