AC runs fine until engine warms up

Tiny
SAMD74
  • MEMBER
  • 2002 OLDSMOBILE BRAVADA
  • 130,000 MILES
The ac will run really cold until the engine warms up and than the clutch will kick off. If its cool out it will last a little longer but have the same end result. Ive tried turning the car off and back on with no success. It will only work once the car has cooled down
Friday, June 15th, 2012 AT 2:12 PM

11 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check to seee if lthe system is full. You may have what's called freeze up and for this apro should look at this and fix it.
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Friday, June 15th, 2012 AT 2:21 PM
Tiny
SAMD74
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  • 14 POSTS
I JUST HAD THE SYSTEM FLUSHED AND REFILLED. I checked both hi and low sensors by bridging them. Im lost.
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Friday, June 15th, 2012 AT 5:42 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Ok then check your actuators in your hvac unit, they may sticking, losing vacuum or electical if they are that. I'll send a generic pic along. Also your pressure switch on teh evaporator may be bad, but you should still have the pressure checked, it could be a blockage in the hi pressure line where the filter is. When you jumped the low pressure switch did it kick the clutch on? If not it may be another problem like the high pressure switch on the compressor is kocking it off. It really needs a set of gauges on it to see what 's happening.
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Friday, June 15th, 2012 AT 6:05 PM
Tiny
SAMD74
  • MEMBER
  • 14 POSTS
Just read the low and high pressure with gauges engine not ruining the low is about 100 at 80 ambient temp and the high side is around 50 what are the causes for this?
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Friday, June 15th, 2012 AT 6:45 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
First the engine has to run so the compressor does as well. Although if the high side is at 50 that is way to low an dsounds like you have aleak 100 on the low sideis a little high but not much. Teh red gauge is high, low is blue. I don't know your expertise so that is why i'm saying this.
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Friday, June 15th, 2012 AT 7:00 PM
Tiny
SAMD74
  • MEMBER
  • 14 POSTS
Could there be a chance that the accumulator or orifice tube are plugged up? Would that cause the above problems?It seems that when the car cools down over night that the pressure subsides and the ac runs again.
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Friday, June 15th, 2012 AT 9:32 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
That's what i've been trying to explain. I t won't be the accumalator as what happens there is the desecent bag breaks an fplugs teh orfice tube filter.
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Friday, June 15th, 2012 AT 10:43 PM
Tiny
SAMD74
  • MEMBER
  • 14 POSTS
Do you think I should change both while I have the system open?Is there anything else I should replace while I have the system open and empty?
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Friday, June 15th, 2012 AT 11:40 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It's hard to say, you should really see what your pressures are BEFORE you open it up. Also make sure to pumpit down for about 15 minutes, do a freon sweep and pump again before charging the system. If you have one of those BUG screens in front of the condensor to keep the bugs out, take it off and throw it away it decreases air flow by 15% that could be a cause as well.
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Friday, June 15th, 2012 AT 11:43 PM
Tiny
SAMD74
  • MEMBER
  • 14 POSTS
I just changed the orfice tube and accumalator and it still does the same thing. I put a gauge on the low side and when the compressor was running the pressure was normal. Than suddenly the compressor would kick off and the pressure would spike. If I shut the car off and came back and checked after about a half hour the comp would kick back on and the pressure would drop a bit, but just for a few minutes, because the car was still warm. This problem has me nuts! What would be making the pressure jump so quickly? Could the high pressure switch have anything to do with it?
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Saturday, June 23rd, 2012 AT 3:01 AM
Tiny
SAMD74
  • MEMBER
  • 14 POSTS
Now I'm really puzzled I checked the pressure this morning and it was still 100 on the low side. Usually it drops down over night. Would there be any other sensors that would be affecting this pressure spike?
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Saturday, June 23rd, 2012 AT 1:49 PM

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