Slow to Cool - High Side 'Too High' 2010 Chevrolet
Posted: Sat Aug 12, 2017 9:03 pm
Have a 2010 Chevrolet Corvette automatic w/ standard LS3 motor.
Last summer the car would occasionally take 1-2 minutes to start cooling.
This summer in the afternoons it is taking up to 5-7 minutes before it starts cooling. The RH side vents will show signs of cool air about 30 seconds before the LH vents. This issue ONLY occurs after the vehicle has sat for an extended period of time in the sun - about 3-4 hours in the afternoon. If the car sits for say 1 or 2 hours - no problem. No variation in the HVAC head unit settings seems to have any affect on the issue, auto/manual, recirc, dual mode on/off, cyclcing the on/off, etc...
Once it starts cooling - it is VERY cold. Going home in the afternoon on a 105F, outlet temps can hit 40 or even lower.
Since I only have a shot once a week on a Saturday or Sunday afternoons at troubleshooting - I really haven't made much progress. Here's what I've observed.
When it occurs the compressor IS engaged but the cool line is not cold to the touch - it remains relatively warm/hot from high ambient temps. At about 5 minutes the low side line gets cool to the touch. Same time the air starts cooling at the vents. This tells me there's probably nothing wrong w/ the air blending box.
I haven't had a chance to duplicate the issue w/ gages but here's what the gauges say when it is cooling at about 100F 50% humidity. Low side: 50PSI; Hi Side: starts at 275 can climb as high as 350 or sometimes higher - approaching 400ish when it's real hot and idling a while. Hi side seems way too high.
Service history: Under warranty dealer treated for 'smelly socks' odor and replaced the HVAC head unit - that was in 2012 when it was 2 years old. Nothing since then and no indication of refrigerant work.
Other than the miserable first 5 minutes driving home in the afternoons in 105F - it really blows cold. But that 5 minutes lasts an eternity w/ a black interior and a 130-140F interior temp. And I'm bothered by what seems to be a rather high pressure on the high side.
Overcharge? (which seems strange given it appears to be a factory charge from 7 yrs ago), Blockagage? ...
I'm going to try and duplicate it again and this time study the gauges while it's not cooling. My concern w/ taking it to a shop is that they'll not be able to readily duplicate the 'slow to cool' issue because it can only be duplicated once a day. They can of course see the high pressure reading any time.
Last summer the car would occasionally take 1-2 minutes to start cooling.
This summer in the afternoons it is taking up to 5-7 minutes before it starts cooling. The RH side vents will show signs of cool air about 30 seconds before the LH vents. This issue ONLY occurs after the vehicle has sat for an extended period of time in the sun - about 3-4 hours in the afternoon. If the car sits for say 1 or 2 hours - no problem. No variation in the HVAC head unit settings seems to have any affect on the issue, auto/manual, recirc, dual mode on/off, cyclcing the on/off, etc...
Once it starts cooling - it is VERY cold. Going home in the afternoon on a 105F, outlet temps can hit 40 or even lower.
Since I only have a shot once a week on a Saturday or Sunday afternoons at troubleshooting - I really haven't made much progress. Here's what I've observed.
When it occurs the compressor IS engaged but the cool line is not cold to the touch - it remains relatively warm/hot from high ambient temps. At about 5 minutes the low side line gets cool to the touch. Same time the air starts cooling at the vents. This tells me there's probably nothing wrong w/ the air blending box.
I haven't had a chance to duplicate the issue w/ gages but here's what the gauges say when it is cooling at about 100F 50% humidity. Low side: 50PSI; Hi Side: starts at 275 can climb as high as 350 or sometimes higher - approaching 400ish when it's real hot and idling a while. Hi side seems way too high.
Service history: Under warranty dealer treated for 'smelly socks' odor and replaced the HVAC head unit - that was in 2012 when it was 2 years old. Nothing since then and no indication of refrigerant work.
Other than the miserable first 5 minutes driving home in the afternoons in 105F - it really blows cold. But that 5 minutes lasts an eternity w/ a black interior and a 130-140F interior temp. And I'm bothered by what seems to be a rather high pressure on the high side.
Overcharge? (which seems strange given it appears to be a factory charge from 7 yrs ago), Blockagage? ...
I'm going to try and duplicate it again and this time study the gauges while it's not cooling. My concern w/ taking it to a shop is that they'll not be able to readily duplicate the 'slow to cool' issue because it can only be duplicated once a day. They can of course see the high pressure reading any time.