Odd HVAC Problem
06-27-2010, 12:45 PM
#1
Senior Member
Thread Starter
Odd HVAC Problem
Searching didn't turn up any definitive answers so here's the problem:
The car runs perfect with the HVAC turned off. Idle is good. power is good. everything appears to be perfect with the HVAC off.
When I turn the HVAC on, either just vent or the AC, the voltage gauge fluctuates, the temp gauge spikes very quickly, and the oil pressure drops on the gauge. If you don't shut the HVAC off fairly quickly, it will load up enough unburnt fuel to shoot a flame out the tailpipe.
We initially thought it was just when the AC was on, but it also happens on just the vent setting.
The car is a 1988 GTA with the digital dash. The motor was just replaced with a 383 and the chip was updated for the new engine. The blower motor was replaced about 4 months before the engine.
The car runs perfect with the HVAC turned off. Idle is good. power is good. everything appears to be perfect with the HVAC off.
When I turn the HVAC on, either just vent or the AC, the voltage gauge fluctuates, the temp gauge spikes very quickly, and the oil pressure drops on the gauge. If you don't shut the HVAC off fairly quickly, it will load up enough unburnt fuel to shoot a flame out the tailpipe.
We initially thought it was just when the AC was on, but it also happens on just the vent setting.
The car is a 1988 GTA with the digital dash. The motor was just replaced with a 383 and the chip was updated for the new engine. The blower motor was replaced about 4 months before the engine.
07-19-2010, 06:55 AM
#2
Senior Member
Thread Starter
Re: Odd HVAC Problem
Back to the top.
Checked the grounds and made sure all of them were on clean unpainted surfaces with clean wires. The problem is still there but very intermittent and it still only happens when the AC and or blower motor is running and usually only after they have been running long enough for the engine bay to heat up.
Checked the grounds and made sure all of them were on clean unpainted surfaces with clean wires. The problem is still there but very intermittent and it still only happens when the AC and or blower motor is running and usually only after they have been running long enough for the engine bay to heat up.
07-19-2010, 01:29 PM
#3
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Scan Plan For A TransAm
You might have a defective temperature sensor, which is reporting to the ECM the engine is cold, when in reality it’s hot.
Beg, borrow or steal (but not mine) a scanner so you can quickly look at the sensors to see if their reporting correctly.
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Happy Racing!
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I Didn’t Jump The Start, The Flagman Was Late
.
Beg, borrow or steal (but not mine) a scanner so you can quickly look at the sensors to see if their reporting correctly.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Didn’t Jump The Start, The Flagman Was Late
.
07-19-2010, 01:50 PM
#4
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Car: 87 Iroc Z 28
Engine: 355/ 600 Holly
Transmission: 700R4 shift kit & vette servo
Axle/Gears: 9 bolt 3;70s
Re: Odd HVAC Problem
My car is carberated but I had the same problem with my gauges when I turned on the HVAC. I had a shorted wire to my temp senser to my elec rad fan.
07-19-2010, 03:06 PM
#5
Senior Member
Thread Starter
Re: Odd HVAC Problem
Working on getting a scanner on it to see what it is doing. The car doesn't normally throw any codes when this happens.
I will check the temp sensor wires though to make sure everything in is wire loom to reduce the chance or accidental grounding from a split in the wire. This would possibly explain why it only happens when the engine bay is hot and is intermittent. The wire would have to expanded to expose the core on a small crack in the casing and would need to have bounced just enough to make contact with another piece of metal.
Based on when it happens, I'll start the wire trace with the blower motor and AC wires though and move to temp sensors from there.
I will check the temp sensor wires though to make sure everything in is wire loom to reduce the chance or accidental grounding from a split in the wire. This would possibly explain why it only happens when the engine bay is hot and is intermittent. The wire would have to expanded to expose the core on a small crack in the casing and would need to have bounced just enough to make contact with another piece of metal.
Based on when it happens, I'll start the wire trace with the blower motor and AC wires though and move to temp sensors from there.
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