Hello everyone,
First post here, but I've had tons of issues since I bought my 07 GXP with the 5.3L used 3 years ago. Have had issues with the wiring system causing the to engine cutting out (last owner hid an accident based on all the underlying damage I discovered over time. My bad on not being thorough enough on the inspection), issues with the Head Light relay (bent the pin that was showing arcing damage after the third one, that seemed to fix the connection and issues for the last couple months), etc. The biggest issue and where I began to suspect the prior accident was the radiator. I've replaced the fan assembly including motor, shroud, etc twice (first failed after 2 years, but never worked perfectly). When I replaced the first one, I found the cross-bar underneath was bent and the original shroud was cracked and causing one of the fans to catch and not turn. Use a trusty 2x4 and mallet to straighten it back down. Got the new fan/shroud mounted and seemed to work better until the temps broke 85. I've taken it to 3 shops to look into it. Most had no clue and said it seemed to work fine and no issue with the radiator. I had the radiator, thermostat, water pump and hoses replaced, bled out and pressure tested at the last shop as they gave the most honest work by actually finding and fixing my electrical issues with the main wiring harness (in under 2 hours) as opposed to keeping the car for a week, not being able to replicate the issue, and suggesting changing out most of the computers and charging me anyway like the others.
Here's the actual situation at question:
Any time the temp outside gets above 85 F and the car idles with A/C on (stuck in traffic or parked), the car temp walks up until it shuts off the A/C or the car overheats. If the car starts driving above 40 MPH for a bit, air-flow brings the temp back down. If you spray the radiator with water, instantly goes back down. If you drive in 85-100 F temps with A/C off. No issues. Fans kick on when they're supposed to and are running when the issue happens. Only mods I know of are that the previous owner threw a Cat-Back system on and removed the Cat's. Had to use a Tune to turn off the O2 sensor checks/errors (otherwise it impacted mileage). I get great mileage (24-32 Highway depending on speed.) Drives fine in general and air blows cold until it gets shut off/system shuts it off.
Is this maybe just an inadequate after-market fan? Should I look for higher end fans from other companies? Need to vent the air flow some other way? Separate transmission cooler to take load off the radiator? Some other piece of equipment that needs to be looked at? Again, only at idle. Only 85F+ outside temp. Only when A/C is on (which OF COURSE I want it on at that temperature.) Oh yeah, environment is wet heat. Live in Michigan, so figure 50-80% humidity at least during the 85F+ temps. Overall, I love the car, issues aside and would love to put this issue to rest. Thanks anyone who has a thought or help.
Originally Posted by cheatah faheatah
