diagnosing a/c problem

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Hello and good morning everybody.

Been having a problem with my air conditioning latley.

Truck is a 2002 Chevy Trilblazer.

Was not blowing real cold and would get worse the more you drive it .

Took it to my normal guy who does all of the work I am unable to do myself and he charged the system with refrigerant.

He checked for leaks with his sniffer and could not find any , even after having it all night and checking the next day .

Worked fine for a couple of days taking a short trip to work , 10-15 minute drive .

On the third day I ran some errands after work and around the 20 minute mark the air started getting warm again and

remained that way the rest of the trip.

Next morning the air was cold on the short trip to work .

Would this be a sign of a bad condensor and hopw could I be sure of what part is not working correctly in the system ?
 
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Could be icing up. Drive until it stops working then pull over leaving the engine and the A/C on and look under the hood. Look for ice on the lines at the firewall, and also look to see if the compressor is engaged or not.

If the compressor is not engaged and the lines are not cold that would likely be the compressor clutch or an electrical problem.
 
Electric or mechanical fan / fans .

As someone asked , is the compressor cycleing ?

Difficult to say a lot w/o hooking up a set of guages to it .

May have to vacuum the system down & charge by weight .
 
Thanks for the ideas so far .

The original problem seems to have not been fixed by the recharge.

The symptoms are the same and on a couple fishing trips ( before the recharge ) I would drive a little over an hor each way .

Good reminder to check the cabin filter meaning to do that anyhow as it has been a while.
 
Check the blend door for the hot/cold mix. My relatives have one and that was an issue with the a/c.

Check the mechanical fan too, I think that was also a problem.

Belt tension good?
 
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Not sure how the system was charged , how would I check the blend door ?

I did use the fuse to reset the mix between the floor and upper vents a couple years ago as the heat was mostly on the floor .

Heat now blows more even between the floor and upper vents.
 
Originally Posted by Chris142
Originally Posted by matrass
The original problem seems to have not been fixed by the recharge.

Was it charged with a scale or guessing with a can?

That's sort of what I'm wondering.

Was the system properly evacuated and then carefully refilled with the specified amount (and type) of refrigerant?...or did he just add more refrigerant and, has now, really screwed up the system by sending system pressure through the roof..., etc., etc.???

Ed
 
I opened up the aera for the cabin fliter and looked at the evaporator, looked clean and not much debris in there.

Also opened up the grill and checked out the condensor and again not oil on it or glaring areas of damage or bebris.

Took the truck out for a longer ride and here are the results.

Stayed cooler for 15 minutes then started getting wamer , took a quick stop at AA for some cabin filters.

Turned on the truck before leaving AA and sounded like the compressor kicked on an off before getting warm again in 3 or 4 minutes

Second time it got warm stopped at the mechanic and we popped the hood .

Accumulator / dryer was warm to the touch and no icing anywhere .

Compressor was not running but he feels 100% there is a leak as it was low again like when I took it in last week .

Showed me everywhere he went over it with the sniffer last week including the cabin / vents.

Asked and he said he did use gauges to check the pressure .

Have not seen any oil in the engine compartment or on my garage floor.

He wants me to bring it back so he can check the pressure and if it is low put some dye in it and use a UV light to find the leak .
 
Find a better mechanic.

If it gets cold once there is still refrigerant in it.

Very common problem is as the clutch wears, the gap between the plate and the pulley increases. When the gap is too large the electromagnet will not be strong enough to pull it in every time. Because the resistance of copper wire increases with temperature, the magnet does not work as well when it is hot. So you get the classic symptom of works for a while after the car is first started, then quits.

This is easily tested by putting a voltmeter on the clutch plug when it is not working, if there is voltage but not engaged there is a problem with the clutch.

Or less scientifically tested by hitting the clutch plate with a suitable tool (while everything is up and running, this test is dangerous). If it snaps down and starts spinning, the gap is marginal.
 
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I've got a 2012 Nissan Versa with 66k on it. Have never touched the a/c and it blows ice cold. Don't get me wrong, I'm not bragging. But what makes one system bulletproof and another prone to failure? Is my relatively low mileage a factor? Does Nissan have a better record as far as a/c systems go? Or is it just dumb luck.
 
Just had this done by my local mechanic

Originally Posted by Kestas
A good mechanic would have injected UV dye into the system right from the beginning.
 
2X on clutch wear or over spec clutch Gap. The three 2000s era Sable's I've owned in the past clutch wear was common with the Auto Temp systems. Problem usually showed up just after 100K miles. Clutch dropping out after warmed up after a few miles was the symptom.
 
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[Linked Image]
 
So the system is losing refrigerant?

I'm not disputing this clutch clearance thing, but this likely has got nothing to do with it if the system has a leak.
 
You need to go by a pressure temp chart to get max cooling. And most cabin filters are out of the air stream unless fresh air is used.
[Linked Image]
 
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