A/C not working 2015 Kia Sedona

[92saturnsl2]

Wife's 2015 Kia Sedona minvan A/C stopped working, naturally it's required to fail this time of year right before a family trip in July.

Hooked gauges up and this is what I've observed:

A) Tested low side by itself, static pressure after sitting many hours-- it read 110 PSI, way above what it should be.
B) Turned A/C on full blast front and rear (this vehicle has a front & rear evaporator) - low drops to about 50 psi, and within seconds the high side gets to about 240 PSI at which point the condenser fan starts. Once the fan kicks on, the high pressure will drop to around 175 PSI in under 10 seconds, then the condenser fan will stop, and it will build pressure back up to around that 240psi mark. The condenser fan will then kick on, pressure will drop, rinse and repeat. The compressor stays engaged the entire time AC is commanded, this doesn't seem to be leak related.

After shutdown, the low side quickly ramps up to around 100+ psi, while the high side bleeds down.

Any ideas from folks that have experience with A/C repair?

 

[JavierH19]

I'm thinking the txv has failed.

 

[shortyb]

I'm thinking the txv has failed.

Me too. Now, it has 2 evaporators so there is a possibility it may have 2 expansion valves (1 for each evaporator). Or it just have one, and the evaporators have individual lines from the ganged (2 circuits) txv.

 

[JavierH19]

Me too. Now, it has 2 evaporators so there is a possibility it may have 2 expansion valves (1 for each evaporator). Or it just have one, and the evaporators have individual lines from the ganged (2 circuits) txv.

I imagine something as new as a 2015 will have them on both but my old Yukon is odd it has a fot up front but txv in the back but I've never seen it.

 

[Chris142]

What's the outside temperatur?

 

[92saturnsl2]

What's the outside temperatur?

Ambient temp was about 90F when I was doing my testing. There's a separate expansion valve for each evaporator on this vehicle.

 

[Chris142]

Going off an educated guess and 175 as the pressure with the fans running it's undercharged. A dual unit will always have more high side pressure than a single unit.

With the fans running it should stay around 200-220 and not drop to 175 or lower if the fans stayed on longer.

 

[92saturnsl2]

Going off an educated guess and 175 as the pressure with the fans running it's undercharged. A dual unit will always have more high side pressure than a single unit.

With the fans running it should stay around 200-220 and not drop to 175 or lower if the fans stayed on longer.

I agree with that but I think there's more going on here. I shouldn't be seeing anywhere near 100+ psi static pressure on the low side and while I'm no expert, the high side should not be bleeding off into the low side when the compressor shuts off, correct me if I'm wrong.

 

[92saturnsl2]

I want to correct myself in the above post--- 100 PSI static pressure (low / high) is normal for R134A at the temperature & humidity we had yesterday. I looked up a chart and it's spot on.

What has me concerned is how quickly the high/low levels equalize after shutting the vehicle down. Again, I get zero cooling regardless of engine RPM; that seems to point to a stuck open expansion valve but I've learned there's another variable:

This system has a variable displacement compressor that is engaged all the time (no clutch). It has a solenoid attached to it that varies the duty cycle via a swash plate that changes piston displacement. Any way to test this?

 

[zzyzzx]

How many miles are on the vehicle?
I am highly suspicious of the expansion valve. If the vehicle has high mileage and a compressor is cheap enough it might be worthwhile to just replace the compressor and expansion valve.

 

[Chris142]

I agree with that but I think there's more going on here. I shouldn't be seeing anywhere near 100+ psi static pressure on the low side and while I'm no expert, the high side should not be bleeding off into the low side when the compressor shuts off, correct me if I'm wrong.

Static pressure means nothing at this point. Ignore it. And normal for it to equalize immediately after shut down

 

[Chris142]

You may be able to replace the compressor controller if you can find one

 

[shortyb]

I want to correct myself in the above post--- 100 PSI static pressure (low / high) is normal for R134A at the temperature & humidity we had yesterday. I looked up a chart and it's spot on.

What has me concerned is how quickly the high/low levels equalize after shutting the vehicle down. Again, I get zero cooling regardless of engine RPM; that seems to point to a stuck open expansion valve but I've learned there's another variable:

This system has a variable displacement compressor that is engaged all the time (no clutch). It has a solenoid attached to it that varies the duty cycle via a swash plate that changes piston displacement. Any way to test this?

That control solenoid should be electronic activated and you should be able to test voltage/resistance etc. at the harness connection. Had a VW control solenoid go bad and did the same cycling/no cooling as your's. Compressor was still fine, and was able to replace just that control solenoid. Of course, the system had to be recovered and recharged to do it.

 

[Chris142]

That control solenoid should be electronic activated and you should be able to test voltage/resistance etc. at the harness connection. Had a VW control solenoid go bad and did the same cycling/no cooling as your's. Compressor was still fine, and was able to replace just that control solenoid. Of course, the system had to be recovered and recharged to do it.

That valve fails on every vw that ever left the factory. We use to keep them in stock

 

[92saturnsl2]

I'm suspicious of a low charge. I know for sure that the low side schraeder valve is leaking. There's an audible hiss and some oil bubbling as soon as I take the cap off. I don't know if that's the source of the leak-- I assume the cap is there as a failsafe to keep it sealed, but I could be wrong.

My plan of attack is:

Introduce some UV dye into the system with some extra refrigerant and see if anything improves. If it does, I'm on easy street and just chasing a leak.

If not I'm probably looking at the other components-- expansion valve & possibly the compressor control solenoid. There are two expansion valves (two evaporators on this vehicle), the front one against the firewall would be an ordeal-- requires taking the upper intake plenum (surge tank in Kia terms) off, which is a lot of work. With that effort I'd do the 100K service at the same time (spark plugs, etc.). At about 86K on the vehicle right now.

 

[92saturnsl2]

Quick update: After introducing some refrigerant and dye to the system, it started cooling again. A failed condenser revealed itself very quickly under UV light. It's leaking at the very bottom where the dryer tank attaches to the condenser (both are integrated) on the driver's side of it. It's making quite a mess down there, I can see the bubbling where the refrigerant is leaking.

Looks like this will be a condenser / dryer & desiccant replacement and hopefully on the road again quickly.

 

[Chris142]

Quick update: After introducing some refrigerant and dye to the system, it started cooling again. A failed condenser revealed itself very quickly under UV light. It's leaking at the very bottom where the dryer tank attaches to the condenser (both are integrated) on the driver's side of it. It's making quite a mess down there, I can see the bubbling where the refrigerant is leaking.
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Looks like this will be a condenser / dryer & desiccant replacement and hopefully on the road again quickly.

That's a common spot on those cars. Might check with the dealer to see if there's any type of good will repair they will do. If you do it yourself make sure that the replacement is a parallel flow like the original is. I often see low quality condensers that are a serpentine style and that can't remove heat well enough.

 

[KrisZ]

I would shut down the rear climate control zone and see how the system behaves with only the front being active.

 

[92saturnsl2]

I would shut down the rear climate control zone and see how the system behaves with only the front being active.

Rear didn't affect it much. Neither the front or rear would work when refrigerant was low, rear worked fine with the front when I added 16oz refrigerant (along with dye). System capacity is around 39oz IIRC, had to convert it from grams. New condenser arrives Friday, should get it back in business.

 

[92saturnsl2]

Replaced condenser, wasn't too bad a job. Front bumper had to come off, horn, hood latch and a couple other small bits. The factory service manual would have you pulling radiator fans & stuff on the other side, but I didn't see the point. The fan shroud sort of blocks the condenser from coming up and out but it wasn't too difficult to snake it in and out of there. Probably a 2 hour job if I had to do it a second time.

Replaced schraeder valves, o-rings @ the condenser fittings, added some oil. Vacuum for 30 minutes, then let it sit for a couple hours, held vacuum fine. Filled it up with 38oz of R-134A and it's working like a charm now.