2004 GMC sierra slt 5.3, digital duel climate control.

Cold air out of vents at 45 - 50 deg. (used thermometer) until today. Air blowing out at 60 - 70 deg. today. Only after driving 65 mph for 45 min and blower slowed down did I get it to 50 deg. With blower on high will not go below 65 deg. Slow blower down and gets to 58 with engine reved up.

Condensate water is running out of drain. so that is ok.

Checked pressure on system, is same as my s10 and jeep. so that seems ok. 225 high and 50 low at 85 deg. outside.

Also noticed the compressor is not cycling it stays on even when the blower is turned down low.

Drilled hole in evaporator coil box, stuck thermometer in box and air temp is same as at the vent. (means that the climate control from box to vents is working ok).

Help - anyone have this problem before? What else can I check or do? Was not like this until today.

 

sounds like what mine is doing i keep thinkng need to change the filter if there is one by the blower motor not sure but will let ya know if that solves it

 

took blower out tonight, cleaned and put back in (not really dirty), no filter in sight.

 

ok no idea then mine seems like it only works good when its not to hot out

 

You are sure the compressor clutch is staying engaged? Is that plug on the drier loose?

 

If driving fast brings the temperature down, maybe the condenser needs to be blown out, or there is stuff between the condenser and radiator.
Or the sustained higher rpm is what gives the added cooling, and that would point toward low refrigerant level, air in system, or refrigerant has become unmixed from repeated topping off.
If blowing out the condenser doesn't help, my next step would be to pull a good vacuum and weigh in the correct amount of 134a.
Unless the door the brings in fresh air instead of recirculating is stuck open.

 

used a hose to spray water on condensor coil to cool down didn't get any colder air, how do I check the fresh air damper to see if it is stuck open?

 

thanks for the help fresh air in take is broke stuck open and not closing, have to fix