LB7: Recurring A/C Problem

[jbstephenson]

Hey guys, i've got a question about my A/C system that hopefully someone can help me with.

I've owned my truck since December of 2014 and since then ive got through 4 a/c compressors. I don't know if this is an lb7 thing or my truck is a lemon and eats compressors. It happens about the time when you need the ac to work in late april or early may. I had the compressor and some other parts replaced under warranty in October, and everything was working fine the last time I shut the ac off in the fall. But when I started using it again this year it seems to not be blowing very cold. It blows somewhat cool air but not cold.

Has anyone else had this issue? Is there anything that could be frying the compressor or causing it to fail?

 

[Chevy1925]

So many things could be an issue. Sounds like you need a competent shop to look at it

 

[Rodwerx]

What all got replaced with the repairs?

If the condenser and hose set have not been replaced, they are suspect.

Next is the evaporator in the dash.

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[Awenta]

So many things could be an issue. Sounds like you need a competent shop to look at it

This. There's no such thing as a truck eating compressors for no reason. Also you use the ac compressor during the winter too when you defrost the windshield.


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[Chevy1925]

What all got replaced with the repairs?

If the condenser and hose set have not been replaced, they are suspect.

Next is the evaporator in the dash.

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That's taking a stab in the dark. Until you know what's in the orifice tube/filter or take things apart or see pressures on gauges, we know nothing.

 

[Rodwerx]

That's true. But old hoses and weak or cheap condensers are the leading cause of leaks with fast and easy / cheap A/C repair.

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[DAVe3283]

A leak will not destroy a compressor. No oil, the wrong oil, improper evacuation during service, or a bad sensor with a clogged orifice (or overfill) can lead to a compressor failure. Additionally, a junk compressor (new or used, junk is junk) can just eat itself for no reason.

I have a 2003 LB7 with 315k miles and over 9,000 hours on it. Original A/C compressor, evaporator, and condenser. There is no inherent issue with the LB7 A/C system.

As has been said, get it to a competent shop, a competent friend, whatever. With a set of gauges and the knowledge, they will figure out what is wrong without replacing parts at random.

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[zakkb787]

This may be a completely stupid comment but honestly from your description it sounds like you have a freon leak.

 

[six5creed]

What kind of compressors have you been putting on it? Cheap or name brand? If it's the same shop/person been working on it since 2014 it's time for a new shop.

 

[Elgavilan]

Sounds like they need to put some dye in the system to see where its leaking, then make needed repairs after that.

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[DAVe3283]

Please don't use dye. That just gums up the A/C system.

A good shop will have a Freon sniffer that can find the leak. Heck, even my brother has a Freon sniffer. If the shop can't find a leak without using dye, go to a different shop.

From my experience, the leaks are almost always the o-rings on the various fittings in the system. A complete set of o-rings is less than $10. If you want to take a crack at it, get a set of o-rings, a brand new drier, a new orifice, and just install them all. If you're going to blindly throw parts, might as well start with the cheap, common failure parts.

Edit: The orifice isn't a common failure, but since a compressor grenaded in the past, the orifice might have debris in it.

 

[zakkb787]

Please don't use dye. That just gums up the A/C system.

A good shop will have a Freon sniffer that can find the leak. Heck, even my brother has a Freon sniffer. If the shop can't find a leak without using dye, go to a different shop.

From my experience, the leaks are almost always the o-rings on the various fittings in the system. A complete set of o-rings is less than $10. If you want to take a crack at it, get a set of o-rings, a brand new drier, a new orifice, and just install them all. If you're going to blindly throw parts, might as well start with the cheap, common failure parts.

Edit: The orifice isn't a common failure, but since a compressor grenaded in the past, the orifice might have debris in it.

Mine had junk all in it. I got a compressor online for $200 with the drier and orifice and oil and all o rings. 1 year unlimited mile warranty and got a condensor off rock auto for a good deal. Did it all at once and took it to a shop and had them pull a vacuum to clean the lines and put oil in and the manufacture spec of freon. Now it'll freeze you out.

Edit: not telling you to cheap out but that's what I did and so far so good. We will see how long it lasts tho

 

[Chevy1925]

When you blow 4 compressors, it becomes an extremely high possibility to have a blockage in the evaporator or condenser. Then that happens you can have a working system and warm air blowing out of the vents after a while if running.

You damn well should be back flushing the whole system any time a compressor dies. That shit gets thrown through the whole system (even by the orifice tube) and will kill the new compressor in a hurry.

 

[Rodwerx]

There's nothing like the "Black Death" to ruin your A/C fun

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[wilsondiesel]

Please don't use dye. That just gums up the A/C system.

A good shop will have a Freon sniffer that can find the leak. Heck, even my brother has a Freon sniffer. If the shop can't find a leak without using dye, go to a different shop.

From my experience, the leaks are almost always the o-rings on the various fittings in the system. A complete set of o-rings is less than $10. If you want to take a crack at it, get a set of o-rings, a brand new drier, a new orifice, and just install them all. If you're going to blindly throw parts, might as well start with the cheap, common failure parts.

Edit: The orifice isn't a common failure, but since a compressor grenaded in the past, the orifice might have debris in it.

Evacuate the system and shoot nitrogen in then use soapy water to find your leak is a great alternative to the others.

 

[jbstephenson]

I totally forgot I posted about this until just now. Thanks for all the replies. Its been to three different shops, only two performing work, one being a dealer. Condenser, orifice, compressor have all been replaced. Evaporator has never been looked at, I know the blend door motor has gone bad so it blows hot air out the passengers side but is that a contributing factor? I guess I need to take it to a new shop and get the evaporator looked at. I just moved up to Annapolis, MD, anyone know about trustworthy shops in the area?