Our 2005 Liberty has recently had a new ac compressor installed and a new coolant reservoir. Today going into town it did fine. On the way home it was in the high eightys . Turned on the AC and it wasn't very cold. At stop lights it warmed up alot and then after 20 miles (almost to our driveway!) ii overheated. Compressor, freon, fan, relays? What can I check? Thanks for any and all help.
Overheating with AC on
- Thread starter Ikster
- Start date
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Start with the easy stuff first and make sure the electric fan is coming on when the AC is on.
If not, and you know your way around basic 12v wiring, you can pull the two relays that are in the engine compartment fuse box near the battery, and jump pins 30 (always hot from battery) and 87 (output)with a short pice of 14ga wire shaped into a U, or even a paperclip. If the fan didnt work before, but now runs when you jump the relay, then the relay is bad. Then when you jump 30 and 87 on BOTH relays at the same time, the fan speed should increase. Thats how the fan is supposed to work on AC. If the fan still doesnt run, then you need to dig deeper.
That said, my AC didn't cool even though it had a full charge, until I changed the AC condensor in front of the radiator. The fins can get corroded, or filled with crap, either of which seriously reduces cold output by blocking fluid to air heat exchange. If the condensor is dirty or corroded enough, it can also lead to not enough air flow to the radiator, which, you guessed it can then lead to engine overheating.
After I changed the condensor and drier/accumulator and all the lines ( once you break open the AC system, you might as well start replacing the parts and o-rings that are gonna start leaking soon enough), then Giddyup's AC started working perfectly…well at least once she was properly recharged and oiled.
NOTE that the AC condensor, at least on a CRD, has the ****** cooler built into the bottom of it and if you dont get the right aftermarket one, which is seldom available, then you need to add a smaller separate transmission cooler as well, which involves changing some plumbing around.
I DO have a brand new extra Nissen cooler that has the built in cooler that I could sell you at cost plus shipping if you need it.
If not, and you know your way around basic 12v wiring, you can pull the two relays that are in the engine compartment fuse box near the battery, and jump pins 30 (always hot from battery) and 87 (output)with a short pice of 14ga wire shaped into a U, or even a paperclip. If the fan didnt work before, but now runs when you jump the relay, then the relay is bad. Then when you jump 30 and 87 on BOTH relays at the same time, the fan speed should increase. Thats how the fan is supposed to work on AC. If the fan still doesnt run, then you need to dig deeper.
That said, my AC didn't cool even though it had a full charge, until I changed the AC condensor in front of the radiator. The fins can get corroded, or filled with crap, either of which seriously reduces cold output by blocking fluid to air heat exchange. If the condensor is dirty or corroded enough, it can also lead to not enough air flow to the radiator, which, you guessed it can then lead to engine overheating.
After I changed the condensor and drier/accumulator and all the lines ( once you break open the AC system, you might as well start replacing the parts and o-rings that are gonna start leaking soon enough), then Giddyup's AC started working perfectly…well at least once she was properly recharged and oiled.
NOTE that the AC condensor, at least on a CRD, has the ****** cooler built into the bottom of it and if you dont get the right aftermarket one, which is seldom available, then you need to add a smaller separate transmission cooler as well, which involves changing some plumbing around.
I DO have a brand new extra Nissen cooler that has the built in cooler that I could sell you at cost plus shipping if you need it.
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Just reread this and it occurrs to me that the shop that did the AC compressor install should prolly be taking a look at it on THEIR time and dime!!!
That said, I would ONLY let them fix it if you KNOW that they are reputable and if they KNOW what they are doing.
Just my .02
I had the same thing happen to me on vacation; it popped the radiator tank side seal and overheated. Come to find out it was the radiator fan not coming on! Thank goodness the local Advance auto had both of them in stock! I always carry a tool bag with me and replaced them in my VRBO rental unit!
Radiator is plugged. Had the same symptoms. Worked good at lower outside air temperatures. Once it got to the mid 80’s outside the coolant temp would climb with the AC on. Turn off AC and coolant temperature would come back down. I put a new radiator in and it works perfectly no matter how hot it is outside.
In the last 3 years we have replaced the radiator and relays. Just a a month ago we replaced the compressor. Compressor cycles in and our every few seconds. Hope to start testing later today-it's in the 90's here today!
CheddarGau
Full Access Member
I would check and make sure the fan is coming on. They may have unplugged it to get to the AC compressor, it's unlikely, but they may have. Next I would like to know if your reservoir is pressurized (called a surge tank but not an important detail) or if it's just a normal reservoir. The pressurized one will have a rad cap on it, normal one will likely have a yellow lid. If it's pressurized, why was it replaced?
If everything is good, verify coolant level is good. Pressurized reservoir can be check from reservoir or rad. Non pressurized check the rad. MAKE SURE IT'S COLD.... SUPER IMPORTANT! If that good, check coolant flow. Flow can be either bad water pump, stuck thermostat or something plugged. Once you verify flow or no flow, you can start isolating what is causing the lack of flow.
If you have been mixing coolant brands in the past, you may have coolant gelling in your system, which can plug things. Something to keep in mind as well.
If everything is good, verify coolant level is good. Pressurized reservoir can be check from reservoir or rad. Non pressurized check the rad. MAKE SURE IT'S COLD.... SUPER IMPORTANT! If that good, check coolant flow. Flow can be either bad water pump, stuck thermostat or something plugged. Once you verify flow or no flow, you can start isolating what is causing the lack of flow.
If you have been mixing coolant brands in the past, you may have coolant gelling in your system, which can plug things. Something to keep in mind as well.
I tested the fan (direct wired to the battery) and it ran on low speed but it did not run on hight speed. Our radiator is about 2" thick, so does that mean it had heavy duty cooling? Jeep has a trailer hitch on it.
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It sounds like a standard radiator. Most of them came with a tow package, but there was a recall with the gas tank due to rear collisions. The recall involved installing an aftermarket tow hitch to add protection. If it has a wiring harness plug it's factory, if no harness it's the aftermarket install. I got my radiator and fan from Advance auto, but you can check other local auto parts stores. Amazon and eBay have them and are less expensive. It depends on how long you can do without the vehicle while you wait on parts!
CheddarGau
Full Access Member
HD cooling is a clutch fan, with transmission cooler etc.
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