LB7: Intermittent AC

[lutzjk913]

Got a small issue going with the regular cab I picked up for my son.

The air conditioning works intermittent and has no rhythm to how it wants to work. It worked on the test drive and then most of the way home after I bought it. In this time frame of buying it early March and early June ongoing to the shop we used the heat plenty but the ac never worked really that I can remember.


Example 1. Truck sat for 3-4 weeks getting some stuff fixed on it. Picked it up from the shop and the ac worked fantastc. Worked really well for a few days at this point then one day it didn’t.

Example 2. Last night I took a stab at it and replaced the ac clutch cycling switch on the dryer. It worked great for about 10 mins and then died off and got hot.

Example 3. This morning I fired the truck up and it worked for 3-4 minutes and then died off and got hot.

Going to look at it further but was looking for ideas or if anyone has had a similar issue.

Thanks, joe

 

[Bdsankey]

Got a small issue going with the regular cab I picked up for my son.

The air conditioning works intermittent and has no rhythm to how it wants to work. It worked on the test drive and then most of the way home after I bought it. In this time frame of buying it early March and early June ongoing to the shop we used the heat plenty but the ac never worked really that I can remember.


Example 1. Truck sat for 3-4 weeks getting some stuff fixed on it. Picked it up from the shop and the ac worked fantastc. Worked really well for a few days at this point then one day it didn’t.

Example 2. Last night I took a stab at it and replaced the ac clutch cycling switch on the dryer. It worked great for about 10 mins and then died off and got hot.

Example 3. This morning I fired the truck up and it worked for 3-4 minutes and then died off and got hot.

Going to look at it further but was looking for ideas or if anyone has had a similar issue.

Thanks, joe

Wiggle the connectors and see if it changes the clutch cycling. My cycling issue was a bad connector at the pressure switch at the compressor. Doesn't help my A/C sucks in my opinion (not super cold above ~80f) but it also is 100% getting replaced this winter when the black box comes out for mode control doors. I'll be doing evap core, heater core, blower motor, motor resistor, all blend door actuator motors, checking all doors, 100% cleaning the box etc as well as new condenser, new receiver drier, orifice tube, pressure switches, new hoses etc.

 

[lutzjk913]

Wiggle the connectors and see if it changes the clutch cycling. My cycling issue was a bad connector at the pressure switch at the compressor. Doesn't help my A/C sucks in my opinion (not super cold above ~80f) but it also is 100% getting replaced this winter when the black box comes out for mode control doors. I'll be doing evap core, heater core, blower motor, motor resistor, all blend door actuator motors, checking all doors, 100% cleaning the box etc as well as new condenser, new receiver drier, orifice tube, pressure switches, new hoses etc.

I will look into that tonight.

Thanks.

 

[DAVe3283]

Have you thrown gauges and a scan tool on it? Without gauges to see the pressures and a scan tool to see what the computer is trying to do, it is really hard to diagnose. In many states, auto part stores (Autozone, O'Reilly, etc.) will lend A/C gauges. Even without a scan tool, the gauges will give you a lot of insight into what is going on.

 

[lutzjk913]

Have you thrown gauges and a scan tool on it? Without gauges to see the pressures and a scan tool to see what the computer is trying to do, it is really hard to diagnose. In many states, auto part stores (Autozone, O'Reilly, etc.) will lend A/C gauges. Even without a scan tool, the gauges will give you a lot of insight into what is going on.

Going to try and get a set of gauges on it tonight to watch and see what happens on them

 

[2004LB7]

When the AC seems to not be "working" is the clutch still engaged or does it drop out? If it drops out try jumping out the low pressure sensor and see if it continues to run. If it does then likely low on refrigerant. IE: a leak

If it continues to run but no cooling, it can still be low on refrigerant and icing over on the evaporator, dirty condenser, bad fan clutch, over charged refrigerant, etc.

This is when a set of gauges helps a lot in figuring out what it is doing

 

[dan.kiger.18]

What's the high side reads, I bet it's really low and the AC isn't doing well on high humidity days

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[lutzjk913]

I will follow up once I get gauges on it.

I went to lunch in it and it worked fine for over 20 mins. Blew ice cold air.

 

[Chevy1925]

Sounds electrical to me.

You try the blend door reset? Regardless of manual or auto, I’ve found pulling the hvac fuse reset deal works on either

 

[lutzjk913]

Sounds electrical to me.

You try the blend door reset? Regardless of manual or auto, I’ve found pulling the hvac fuse reset deal works on either

I would have to agree with you.

We checked the pressures and they check out good.

The tech at work thinks the control head is junk in it. The reason he says that is because if you start messing with the switch inside it stops working. And then if you unplug it and plug it back in it works fine for a while. I did it twice on the way home and it restarted and worked fine both times.

I have a extra control head I am trying at the house now.

 

[lutzjk913]

Put a extra control head I had at the house in it. Worked fine for 20-25 mins. Cycled off and on and off and on. Went for a drive and it worked great.

Come back. Put the truck dash back together and it it immediately did it again. Same stuff as before. I tried shutting the truck off and on and nothing. It didn’t change.

 

[DAVe3283]

Sounds like it is time for a scan tool. See if the ECU is receiving an A/C request or not. See what it sees for high side pressure. (Low side switch will present as a lack of A/C command despite the control module showing A/C on.)

 

[lutzjk913]

Sounds like it is time for a scan tool. See if the ECU is receiving an A/C request or not. See what it sees for high side pressure. (Low side switch will present as a lack of A/C command despite the control module showing A/C on.)

Any idea on what scan tool is needed?

 

[Chevy1925]

Efi live should show it if I remember right

 

[M.A.M.]

My scanner will work. Don’t know if I’ll be down your way anytime soon or not tho.


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[lutzjk913]

I texted one of my customers. We are going to check it out next week.

He’s the one who did the airbag stuff for me also

 

[DAVe3283]

Efi live should show it if I remember right

That's what I use. Ironically, the Tech2 doesn't show A/C high side pressure, but EFILive does.

 

[TheBac]

Well, thanks for this. BBT's A/C went out about a month ago. I havent even started diagnosing it.

 

[lutzjk913]

Had my buddy/customer check it out.

He went through what I did. We swapped out the high side switch and then the compressor also. It’s still doing this.

All he had was a tech 2 and it doesn’t read high side pressure like said before.

We did find out that it had a U1152 code I believe which comes back to the HVAC module.

He wants to do some further diagnosing on it so I am dropping it off next week.

 

[Hambone]

Is the clutch still engaged when the ac stops blowing cold?
When you say pressures are good what are they idle and under light acceleration?
When the blend door deal goes bad the compressor still stays on
Was the compressor a acdelco or parts store?
Did he replace the accumulator and orfice when he did the compressor?