AC Compressor is probably shot - estimate cost?

[TridenT]

Fun fact - winchill is actually 'windheating' when air temp is above your body temp. You likely should have driven with the windows barely cracked to prevent solar from overheating your car, rather than all the way down.

Yes, but in the situation I was in... somehow windows down felt better. I can't remember the actual temp (I think something like 95F) but yeah... whatever.

I'll be buying a cooler tomorrow and then filling it with ice before I leave... I'll probably buy some bits of equipment to test my AC while I'm in Phoenix and then I'll fix it while I'm there. I have a free place to stay while I'm there and access to lots of tools and a garage. So, that's why I'm hesitant to fix my AC at a mechanic right now. I could save $500+ by just doing this myself...

105F Heat index isn't anything.... Other than they oddly cool summer this year, that is normal Chicago July -> August temps.

It's really high for Seattle. That's where I've lived for the last 3.5 years.

 

[jlee]

It's low 100's in Phoenix now. It's not terrible. 115 was a month or two ago.

 

[olds]

It's low 100's in Phoenix now. It's not terrible. 115 was a month or two ago.

Ya, but it's a dry heat.

 

[jlee]

Ya, but it's a dry heat.

Yup. I love it here - no regrets.

 

[Zenmervolt]

Ya, but it's a dry heat.

So's my oven.

ZV

 

[TridenT]

Got AC Gauges today in Austin from harbor freight. ~$51.

Hooked them up, got an initial reading (didn't record it unfortunately), and then turned the car on and put the AC on. It's 97F out with 34% humidity (iPhone weather app says).

Low side was rock steady at 39 psi. High side was also rock steady at 125 psi. They didn't move at all from those positions either. No movement at all. Turned the car off and they stayed at those readings and I disconnected the gauges.

Before I turned the car on (I had just driven to harbor freight and back) with the gauges attached, I had a slightly lower reading on both sides from what I remember. The AC was never on for those trips.

I'm not sure what to interpret of that. The lowside is low for the heat out and so is the high side. From what I looked online, it should be about 50-55 psi for the lowside and 315-325 for the high side.

But with the readings never changing, would that indicate the AC Compressor is shot or possibly low on refrigerant? (It is spinning from what I could see)

EDIT: Maybe I'm wrong but I thought the gauges would move to indicate that the system is changing pressures and so forth... But maybe these ones just take the highest pressure and put that down? I don't know. I'll have to read the manual better. I watched an eric the car guy video where he diagnosed the AC of a car and the gauges were moving and he said that's a good sign.

 

[Zenmervolt]

Got AC Gauges today in Austin from harbor freight. ~$51.

Hooked them up, got an initial reading (didn't record it unfortunately), and then turned the car on and put the AC on. It's 97F out with 34% humidity (iPhone weather app says).

Low side was rock steady at 39 psi. High side was also rock steady at 125 psi. They didn't move at all from those positions either. No movement at all. Turned the car off and they stayed at those readings and I disconnected the gauges.

If the pressures do not equalize when the system is off, you have a clogged or stuck expansion valve.

With the system on, you should be seeing higher pressures on the high side (around 200 PSI at the temperature you measured at). This is especially true if the expansion valve is stuck. So it sounds as though, in addition to the stuck expansion valve, your compressor is also not engaging.

The expansion valve is buried under the dashboard somewhere and can be a pain to access.

To do this repair properly, you will need to evacuate the system (you'll need an approved refrigerant recovery system to do this legally, or you'll have to pay a shop to do it). You'll also need to replace a bunch of o-rings in the connections that have to come apart to get at the expansion valve.

EDIT: Also, when recharging the system, the ONLY way to do it properly is to charge by refrigerant weight. You cannot charge based on pressures. It is technically possible to charge based on subcooling, but the design of most automotive systems makes it difficult to get a thermocouple on the line at the proper point and the location of the high-side port for pressure measurement may not be ideal.

ZV