Automotive Air Conditioning Information Forum

A/C has been intermittent on my wife's escalade lately. She'd been mentioning that it's been acting up for the last couple months, but it's been too cold to address. Anyway, I caught it acting up today - A/C on coldest setting (60°F), blower on high, etc, outside temperatures in the high 70's/low 80's, but vents no cooler. Checked under the hood and noticed the compressor was not engaging. Tapped the front of the clutch to see if it was a clutch gap issue to no avail. Hooked up a Tech 2 scanner and evaporator temperature indicated a short, and front evap temp readings were sky high (158 or so IIRC) even though it's a moderate temp day. Oddly, I turned up the temperature for a few moments, then turned it back down, and the compressor engaged and A/C started working again, and stayed working through a couple drive cycles (hasn't acted up since) .

Anyway, all indications seem to point to an intermittent evap temperature sensor problem. Anyone know if you can replace it without dropping the dash? Any tips for performing this job?

It might be just a low charge. A small amount of refrigerant typically leaks from the compressor shaft seal over time. Since your wife's vehicle is now six to seven years old, enough refrigerant might have leaked out by now to begin affecting performance.

Before taking the dash apart (a difficult, time-consuming job), I'd recover the charge first, or have it done, to determine how much refrigerant is in the system. I wouldn't be surprised if it's a few ounces low...enough of a loss to cause the problem you're now beginning to see.

Well, I recharged it tonight - we'll see what happens. There was some confusion regarding specified capacity in the factory service manual - either 2.5 Lbs or 3.0 Lbs, although I _think_ my vehicle should be 3.0 Lbs. I pulled out just 1 ounce shy of 2.5 Lbs...if I was correct on the spec value of 3.0 Lbs, then it was a few ounces low. If not, then it was just about right.

Can anyone confirm whether or not the dash actually has to come out should the evap temp sensor be the culprit?

There should be a sticker under the hood indicating the correct refrigerant charge. Go by that and not any chart.

If your vehicle is the EXT model and has the 6.2L V8 with rear A/C, my source references say that the system capacity is 48 ounces (3 pounds) of R-134a and 11.0 ounces of PAG-46 oil. But as mentioned previously, the under-hood sticker takes precedence over any reference charts.

The non-EXT model with the same engine and rear A/C takes 40 ounces (2.5 pounds) of R-134a and the same amount of oil.

So, yes, I think yours holds 40 ounces (or whatever the under-hood sticker says).