My SUV after setting for a few hours will start lowering the read of SUV. it will correct it self after starting and runing for a few minutes. it also seem to not hold as much weight.
I have absolutely no idea what you are asking. Do you think you could clarify? “start lowering the read of SUV” - ?? “seem to not hold as much weight” - ??
Are you talking about a problem with an auto-leveling air suspension system?
OK did you mean “lowering the rear”?
Do you mean you can measure a higher tyre pressure after it has been running (I assume you men being driven) a few minutes?
Always measure tyre pressure with the tyres before they are driven. Once they are driven, they will show a higher pressure, but it is not what you need to measure when filling the tyres.
If I had to guess you have low pressure in a rear tyre (or more) and when you drive to fill it, then it is higher pressure. If so figure out how many psi it is low when cold and then when you get to the air supply, fill it to the recommended pressure plus how much it increased from where you started.
Note the pressure indicated on the TYRE is NOT a recommended pressure.
When you have to work so hard to figure out just what the heck the OP is saying - an answer is impossible. OP, try to ask this question again if you want some answers.
Here’s what I think - I think the OP does have auto-leveling air suspension and now thanks to Mr. Meehan assume he meant “rear” of SUV.
It corrects itself so apparently the sensor and compressor are working properly. But apparently won’t keep up if you put weight in it.
So…the OP probably had leaky shocks and needs to replace them if s/he wants the air leveling to work. Though the air lines, esp. the o-rings where they connect to the shocks ought to be inspected first.
I think this is the most correct answer and I agree, I was told by a deal it could be the compressor at a cost of about $1000.00 to replace even when I said that the compressor always works.
I have an Olds Silhouette with basically the same system. (I’m sure the Envoy shocks are probably a bot heavier duty). I had a similar problem and replaced both rear shocks for all of about $75 and an hour of my time. Changing shocks is almost easier than changing a tire (fewer bolts). If you don’t want to mess with it yourself, just take it to a local, independent shop. There is no need to use the dealer, and based on your description the compressor is fine - as you suspect.
This is a case where aftermarket parts and an independent mechanic can cut the cost to 50% if you pick someone that can trouble-shoot well.