AC doesn't blow cold air at idle

[jyi786]

2019 Escalade ESV. 130k miles. AC doesn't blow cold air at idle (weak): the air is just slightly cool. When I step on the gas (while it's still in Park/idle), the AC gets cold.

This gets annoying because it won't be cold enough when sitting in heavy traffic. However, any kind of throttle I give it, or when the truck is moving, the AC is ice cold.

I took it to the dealership, and they told me that the AC compressor needs to be replaced. Their diagnostic was that it is "intermittent". They also said they checked the freon levels and that it is fine. This is the same dealership that I just had my transmission replaced at, so while I know they do quality work, I am suspecting whether or not the AC compressor is really bad. They want $2,000 to replace it.

So forums, can you all help me diagnose? There seem to be no radiator fan issues; they do kick on/off appropriately. There also seems to be no leak in my radiator as well. The AC is just weak at idle. Also, no overheating of any kind, either engine or transmission. Any help/suggestions you can provide would be appreciated.

Thanks!

 

[Matthew Jeschke]

With a truck as new as yours... hrm, it's a little early for compressor to fail so I'd be a little skeptical too but can happen.

I'd think a pressure gauge set would be helpful to diagnose a weak compressor. You'll not get good pressure on the high side (it'll be low). Do you have rear air? If so... if that TXV valve and or the orifice tube up front are faulty (open instead of restricting / regulating flow) then you'll have similar symptom. A person would have to open the line set up anyways to do that.

You can also use a mechanic's stethoscope to probe the compressor and listen for grinding noises.
Another possible suspect is a slipping AC belt. This JUST happened to me. The tensioner went out but air was being a little weird. It seems to only work when I was moving cause that's when the belt had enough grip in it to spin the compressor. After a few miles the tensioner went completely out.

 

[jyi786]

With a truck as new as yours... hrm, it's a little early for compressor to fail so I'd be a little skeptical too but can happen.

I'd think a pressure gauge set would be helpful to diagnose a weak compressor. You'll not get good pressure on the high side (it'll be low). Do you have rear air? If so... if that TXV valve and or the orifice tube up front are faulty (open instead of restricting / regulating flow) then you'll have similar symptom. A person would have to open the line set up anyways to do that.

You can also use a mechanic's stethoscope to probe the compressor and listen for grinding noises.
Another possible suspect is a slipping AC belt. This JUST happened to me. The tensioner went out but air was being a little weird. It seems to only work when I was moving cause that's when the belt had enough grip in it to spin the compressor. After a few miles the tensioner went completely out.

Appreciate the feedback! How can I diagnose a slipping belt? Just watch it to see if it spins when the AC is turned on and the compressor engages?

 

[BattleTank]

I'm curious as to how they tested the freon levels as 'fine'.

In my world of diesels and heavy truck mechanics, the only way we can verify how much freon is in a system is by using an a/c machine and recover what's in the system. The machine tells us exactly how much freon was recovered and we verify on the vehicle sticker what the correct amount is.

In your case, even using a set of gauges to see how much pressure is in the system doesn't exactly say how much freon is in it. Fluttering gauges will indicate compressor issues. Gauges that don't move at all indicate the compressor isn't turning on, or the compressor is completely failed.

Keep us posted

 

[Marky Dissod]

I'm curious as to how they tested the freon levels as 'fine'.

In my world of diesels and heavy truck mechanics, the only way we can verify how much freon is in a system is by using an AC machine and recover what's in the system.
The machine tells us exactly how much freon was recovered and we verify on the vehicle sticker what the correct amount is.

In your case, even using a set of gauges to see how much pressure is in the system doesn't exactly say how much freon is in it ...

Besides sucking it out, measuring how much was sucked out, and jamming that much back in plus possibly a wee lil bit more,
there MUST be an independent reference source for exactly how much to put in.

Of course, this reference can still be misused, especially by idiots, but even by humans.

My AC was faltering at idle. So, my unusually busy mechanic looked at the front of my TAHOE, saw a SILVERADO,
and put in the correct amount of freon for a GMT800 pickup - which is not enough for an SUV.
As a result, my AC was faltering at idle again.

How can I diagnose a slipping belt?

Don't know how to answer this question, except that I blindly replace my belts every two years.

 

[BattleTank]

Besides sucking it out, measuring how much was sucked out, and jamming that much back in plus possibly a wee lil bit more,
there MUST be an independent reference source for exactly how much to put in.

Of course, this reference can still be misused, especially by idiots, but even by humans.

My AC was faltering at idle. So, my unusually busy mechanic looked at the front of my TAHOE, saw a SILVERADO,
and put in the correct amount of freon for a GMT800 pickup - which is not enough for an SUV.
As a result, my AC was faltering at idle again.Don't know how to answer this question, except that I blindly replace my belts every two years.

Most Cooltech A/C machines have a built in updatable database of most vehicles in the US. Most if not all US cars have a sticker located in the engine bay that has the freon/oil specs listed. This is why the EPA insists that the every day do-it-yourselfer refrain from doing a/c work.

 

[Marky Dissod]

Most if not all US cars have a sticker located in the engine bay that has the freon/oil specs listed.
This is why the EPA insists that the every day DIYer refrain from doing AC work.

But, since it is a FACT that we have the right to buy R134A and put it into our vehicles' AC compressors, the EPA is half@$$ing by NOT making it easier for DIYers to
drain out old freon
measure the proper amount of new freon

 

[BattleTank]

But, since it is a FACT that we have the right to buy R134A and put it into our vehicles' AC compressors, the EPA is half@$$ing by NOT making it easier for DIYers to
drain out old freon
measure the proper amount of new freon

I completely agree.

Don't get me started on DPF/SCR emission systems on heavy trucks. EPA has down right made it so difficult for mom-pop shops to work on them unless they are sent to the dealer. (I'm 10 years Volvo/Mack dealer)

 

[jyi786]

Update: it was indeed the AC compressor.

Stealership installed new AC compressor, seals, the works. Had my truck back to me in a few hours. While idling, AC at full blast is so cold it can freeze your a** off.

They only charged me $1400, parts and labor. I may not like their prices because they are still a dealership after all, but they have been impressive in taking care of all my needs for my truck so far. They've never been wrong once.

I now have a separate issue which is also getting rectified next week, happened on my way to the dealer this morning: starter is going bad. New one already on order and getting installed next week.

 

[BattleTank]

Ouch.

If I had my own A/C machine, I could put a hurtin on dealerships.

 

[jyi786]

Another update. The AC started acting wonky again. I cleaned the radiator thoroughly (rinsed with coil cleaner), changed the cabin air filter, made sure the AC evap coils were clean, and while it got slightly better, it still was not acceptable.

I took it back to the dealer today, and they diagnosed. There were no leaks anywhere in the system. When they did the initial service to replace the AC compressor, they put dye in it, so they found no trace of dye anywhere.

What they did find?

They discovered the AC was overfilled with Freon...to the tune of .874kg. The techs were confused because prior, they had used the same machine to evacuate and refill to spec. So someone either screwed up or something was wrong with the machine. They again evacuated and refilled to spec: .850kg.

Result? The AC is now ice cold at idle and will freeze you to death during a drive. It was cool/cold before, but not THIS cold. Now it's bone chilling cold, which is how I always remember it is supposed to be like.