Anyone have Overheating issues while running the AC only
Thread Starter
Melting Slicks
Joined: Dec 2005
Posts: 2,074
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From: Charlotte NC
Anyone have Overheating issues while running the AC only
On my way to the track last night I was running the AC as I had my gf with me. Temps rose to 237 coolant before I shut the AC off to see if that cooled it off. This was stop and go traffic but as soon as I turned the AC off the coolant temp dropped dramtically and after a few miles it was below 210 and finally dropped below 200. It usually runs high 190's-210 on a hot summer day here. I doubt this is normal with the AC on. Perhaps its time for a Dewitts and some new fans? Its a 1999 FRC H/C/I car with original stock cooling system.
Burning Brakes
Joined: Dec 2003
Posts: 855
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From: Tampa FL
My Jeep Grand Cherokee started doing it lately. Even after I did a oil/coolant change on it. Its weird because as long as your moving its fine. I am thinking maybe the raidator or the flow is getting messed up somehow .
Le Mans Master
Joined: Aug 2005
Posts: 7,201
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From: DP(oh you know where) IL
St. Jude Donor '06
thats pretty normal with stop and go traffic, but if you want to play it safe, just check to see if there is something blocking the radiator. also, you may just want to loosen up the radiator and get a blow gun and blow whatever is in there out. being a 99 im sure its sucked up a lot of dirt and dust.
Racer
Joined: Dec 2005
Posts: 287
Likes: 2
From: Bay Area California
On my way to the track last night I was running the AC as I had my gf with me. Temps rose to 237 coolant before I shut the AC off to see if that cooled it off. This was stop and go traffic but as soon as I turned the AC off the coolant temp dropped dramtically and after a few miles it was below 210 and finally dropped below 200. It usually runs high 190's-210 on a hot summer day here. I doubt this is normal with the AC on. Perhaps its time for a Dewitts and some new fans? Its a 1999 FRC H/C/I car with original stock cooling system.
A1
Drifting
Joined: May 2000
Posts: 1,917
Likes: 3
From: Southern NH
In stop and go traffic that's not too unusual but it's worth checking out. Remember that if you're not moving the only airflow is via the fans which will only come on when the engine temp rises. For my 2000, the fans will come on at low speed at 219F and high speed at 228F. Remember that with AC on, the fans are drawing air through the AC condenser to remove heat from it which is right in front of the radiator so that heat will have some effect on the engine temp. If you have some debris in front of the radiator that would affect airflow and allow temps to rise especially in stop/go traffic. 237F sounds high but since your temps dropped as soon as you turned the AC off that implies that airflow may be the issue.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
Sounds like an airflow problem ..... here is the fan programming as described in the Service Manual ...
The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).
Notice that the cooling fans come on sooner with the A/C on.
I'd get under the front of the car and check the plenum area in front of the A/C condensor. It is not unusual to find trash that the car has sucked up stuck against the front of the condensor .... newspaper pages, MickeyD bags ..... former Democratic presidential candidates (anyone seen Chris Dodd recently ???) ...... the C5 is a "bottom breather" and easily picks stuff up.
The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).
Notice that the cooling fans come on sooner with the A/C on.
I'd get under the front of the car and check the plenum area in front of the A/C condensor. It is not unusual to find trash that the car has sucked up stuck against the front of the condensor .... newspaper pages, MickeyD bags ..... former Democratic presidential candidates (anyone seen Chris Dodd recently ???) ...... the C5 is a "bottom breather" and easily picks stuff up.
