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Old 07-12-14, 10:44 PM   #1
Jdmsc5spd
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Default Help sc400 overheating with a/c ON

I am stumped I supercharged my sc400 and it only overheats when the a/c is on I can drive 20-30 minutes it is fine any longer it gets hot and will throw a code 55...I replaced the radiator with a koyo 3 row 160 t stat 2 shrouded zirgo fans and water wetter still nothing.... Checked a/c pressures low 35psi / 250psi it does not idle up when the a/c is engaged...any help is appreciated pulling out my hair there is no white smoke or oil in the coolant vice verse only other thing I can think of is a dragging a/c compressor it was making lots of vibration months ago then all the sudden stopped a/c works still or a weak water pump
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Old 07-12-14, 11:09 PM   #2
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What makes you think it's overheating? Code 55 is knock sensor #2.

I had a lot of knock sensor problems a few months back, but they've subsided of late. It happened more frequently when the A/C was on, especially accelerating onto freeway on-ramps. I finally tested it out on the highway with A/C this week and had no issues, "knock" on wood...

The things I did that seemed to have the most impact on cutting back the knock sensor trips were replacing all the dry old vacuum hoses, and getting the bad gas (*$%#@! dealer) out of the system and using several bouts of fuel system cleaners.
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Old 07-12-14, 11:23 PM   #3
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I think it's overheating cause the needle will go past 3/4 and turn the a/c off will come back down....I'll take a look at the vac lines
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Old 07-12-14, 11:38 PM   #4
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Okay, that's sound reasoning.

One of the common causes of knock sensor codes, supposedly, is degradation of the sub-harness because of its location and getting cooked over the years. If your car is indeed overheating, maybe some worn wiring is sensitive enough to trip it?
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Old 07-13-14, 01:09 AM   #5
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Yeah I just replaced a knock sensor plug trying to fix this issue found it cracked and broken on the passenger side of the engine idk if this number 2 or not...still no dice I'm more worried about the over temping
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Old 07-13-14, 03:04 AM   #6
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maybe bad water temp sensor :/
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Old 07-13-14, 09:02 AM   #7
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It's been replaced before but I haven't done the sender
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Old 07-13-14, 01:01 PM   #8
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How is your fan clutch?
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Old 07-13-14, 04:42 PM   #9
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No fan clutch removed hyd fan and installed e fans on a relay if that's what you mean
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Old 07-14-14, 11:31 AM   #10
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Any ideas?
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Old 07-14-14, 05:23 PM   #11
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Quote:
Originally Posted by Jdmsc5spd View Post
No fan clutch removed hyd fan and installed e fans on a relay if that's what you mean
Missed that. Sorry.
Are those fans moving a lot of hot air when they're running?
Does a water spray on the radiator fins help any? Common t-shooting step.
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Old 07-14-14, 11:24 PM   #12
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Yeah they seem to be moving a fair amount of air they are rated at 2700cfm each, yeah when I spray water through the condenser to the radiator it seems to help cool it down I'm going to be adding a extra 8in condensor fan see if that helps it

Last edited by Jdmsc5spd; 07-14-14 at 11:49 PM.
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Old 08-01-16, 04:48 PM   #13
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It's crazy how many people don't come back to tell us if and how they resolved their problem.
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Old 08-08-16, 08:00 AM   #14
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Sry forgot I replaced zirgo fans with 18in the thinder bird fan and put one 10in pusher fan and cut a vent in the hood where the supercharger is and found a bunch of unseen leaks on heat lines and heater valve cracked. For the code I replace knock sensor plug so far so good a/c on in 115 here in Vegas I get as high as 230f im usuallly still around 210f-220f i usually run about 180f-200f with no a/c..if I start to get warm I installed a water sprayer for intercooler and condesor. Soon I'm going to get a vented cf hood should help a lot
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