2014 GMC Sierra AC

Hey Scott , FYI on the acetone .

I did this exact thing 2 years ago on my 91 bronco , the interwebs says don't use acetone , even though its a great flush , once you get the vacuum pump on there its very volatile and the fumes / pump could make everything go boom .
It's probably overly cautious , but thats why I went with the standard flush stuff.

And hold the vacuum for several hours to ensure the system is nice and tight.

Good luck

since today is a half day, will start teardown around noon..... unless its raining

Redrig said:

could make everything go boom .

Click to expand...

wouldnt be my first explosion, however will be working outside in the breeze, so not too concerned with vapors

Currently raining....... Out of nowhere

Glitter fairy dust from the evap coil


Cleaning out the lines (first flush)



Misc photos of tear-down











Wire brushed the melted rubber off the damper, then hit the damper with a rattle can of paint

Have 2 new condensers thanks to Amazon screw up

Just waiting for rain to stop to do second flush with acetone, then final with AC flush

Then assembly

Finished up today

Used a gallon of acetone and a can of flush to clean the glitter fairy dust from the hoses and evap core



The acetone swelled the seals in the cheap Amazon blow gun in the flush kit

Did all GM parts for warranty reasons, even though there are better built condensers out there like the units I used 3 years ago from NAPA



Adding the oil to the compressor took nearly 30 minutes of dribbling in oil and turning the compressor

The manual says 0.6kg of freon or about 21 oz. However the gauges say it's closer to 28oz. Pressure was low at 170 psi until I added another 6 oz, then high side got up to 300-305psi, low side at ~50 (94F ambient temperature)..... Perfect.,.........

Then my 25 year old manifold hoses blew. 3 pin-holes in the high side.


Tried adding more with just monitoring the low side, however I can't tell if I am under charged or over charged.

Ordered a new set of hoses, they arrive Monday

Nice write up Scott, almost have me convinced that I could do this, how did you determine what to replace. Did you keep all the old lines and stuff. My ac hasn't worked in years, I used to get by adding a can every summer but that became twice a summer. It might last a day or two now.

The compressor locked up, so the compressor needed replacement

Every time you open the system, you replace the H block and the drier (in the condenser on the truck)

The condenser in the truck is a 2-pass so they can not be flushed. So have to replaced.

The lines and evap core can be flushed.

All new seals, the proper oil per compressor and done ..

flashback said:

Nice write up Scott, almost have me convinced that I could do this, how did you determine what to replace. Did you keep all the old lines and stuff. My ac hasn't worked in years, I used to get by adding a can every summer but that became twice a summer. It might last a day or two now.

Click to expand...

Put some die in the system. Find out where the leak is

My old truck is a 2001 Sierra 1500, has several small things wrong with it, and I don't use it often anymore, I will get some dye and see whats leaking if I can get off my butt.

You will need a UV light and the special glasses. I got mine from an auto store about 30 years ago, Amazon has them for about $10

New car dealer do use speciality repair shops.

cyclops222 said:

New car dealer do use speciality repair shops.

Click to expand...

Huh?

Closing this out.

Amazon brought new hoses and I swapped my service connections

Checked pressures against the chart





Air out the vents just below 60F with a 91F ambient

update from the camping trip in Tennessee. the AC worked flawlessly for about 80% of the trip up to Chattanooga. however the AC started cycling the last hour and half.

thats 8.5 hours into a 10 hour trip (680 miles) .... get the site set up..... drink a beer or three

look at it the next day.... worked fine for about an hour, then it started cycling again.

it would be fine for a while, then the compressor starts cycling. put a low-side gauge on it from the emergency kit (freon can with low side gauge). pressure was 43psi (low for 93 ambient - should be about 45-50 psi). so adding just a little, and the pump cycles more often indicating the high side of the switch is dropping it. drop the pressure slightly and the compressor stays running for well over an hour. suspecting the high-side of the binary switch is going belly up as the temperatures were only in the low 90's which was cooler than the past few weeks in FL

a bit over 90 minutes later, just as we get to ATL...... the AC stops. with an occasional bit of cool. make it thru the parking lot known as I75 in Atlanta....... so drop the system pressure slightly at a truck stop south of ATL to get the compressor to stay on. it stayed running for about another 6 hours and then started cycling again.

looks like a new binary switch is in the works now. the downside is the system will most likely need to be fully evac'd and recharged unless there is a schroeder valve under the switch

lesson to learn folks. swap the binary switch when you swap the pump if you use a solvent to flush the lines. I suspect the switch wetted surface may not have liked the solvent.

second lesson to learn. Rock Auto does not list a switch. had to go to the GMpartsdirect diagrams to get the GM part number of the delco switch.

GM 13587668 / 1551343 or FourSeasons 20915

High side switch has valve below it
I believe you have air or charge is off...l usually introduce oil threw yellow line as most compressors ship with enough oil for start up.
Possible EAT sensor wacky

compressor came with shipping oil. was only 1.3 oz (40cc). with clear instructions on filling the compressor to a total of 6.5oz.

have a new binary switch on its way.

Before you start chasing your tail on this one check the EAT sensor...sometimes known as evaporator temperature sensor
It's in evaporator ...your truck if you look up above gas pedal ...at back by firewall of evaporator...2 wires plugged into it. Signal goes direct to ECM ...can shut down system or erratic operation similar as you described. Thats if you don't have a leak or bad charge condition ...like overcharged
I don't believe high pressure switch is your problem as it usually shuts system down.