Ac Cooling

[JoeBoxer1130]

2003 Tahoe LT
Does anyone know why my ceiling AC vents blow out colder air than the front vents???
Im not low on coolant last time I checked.
Any tips will be greatly appreciated.

 

[TJ Baker]

2003 Tahoe LT
Does anyone know why my ceiling AC vents blow out colder air than the front vents???
Im not low on coolant last time I checked.
Any tips will be greatly appreciated.

Simplest answer is the two vents come from different evaporators.

The air from the ceiling outlets comes from the auxiliary system and the air from the panel vents comes from the front system.

Further, the front system employs a fixed orifice as a refrigerant meterimg device and the auxillary system uses a thermal expansion valve.

A TXV (thermal expansion valve) system can maintain better control of the evaporator core temperature than a fixed orifice system can.

That's my guess....

 

[PG01]

Simplest answer is the two vents come from different evaporators.

The air from the ceiling outlets comes from the auxiliary system and the air from the panel vents comes from the front system.

Further, the front system employs a fixed orifice as a refrigerant meterimg device and the auxillary system uses a thermal expansion valve.

A TXV (thermal expansion valve) system can maintain better control of the evaporator core temperature than a fixed orifice system can.

That's my guess....

Pretty got-damn good guess if i do say so myself….

 

[mikez71]

Could said fixed orifice be clogged, causing sub optimal cooling?
Hopefully relatively easy/cheap to replace? (though still requiring a charge)

If the front blend door actuator was failing/partially stuck? .. are you able to blow heat in the front?

And are you on recirculate?
I once noticed fresh air was really warm with my A/C off, though I was missing my cowl seal at the time..

 

[JoeBoxer1130]

Could said fixed orifice be clogged, causing sub optimal cooling?
Hopefully relatively easy/cheap to replace? (though still requiring a charge)

If the front blend door actuator was failing/partially stuck? .. are you able to blow heat in the front?

And are you on recirculate?
I once noticed fresh air was really warm with my A/C off, though I was missing my cowl seal at the time..

Could said fixed orifice be clogged, causing sub optimal cooling?
Hopefully relatively easy/cheap to replace? (though still requiring a charge)

If the front blend door actuator was failing/partially stuck? .. are you able to blow heat in the front?

And are you on recirculate?
I once noticed fresh air was really warm with my A/C off, though I was missing my cowl seal at the time..

Yes, hot air comes out when I bring it up to 90F

 

[RET423]

Feel the larger line connected to the evaporator where it comes out of the firewall, if it's very cold then your blend door isn't closing off the heater core all the way in the front section; these doors are controlled by electric blend door actuators that are simple to change & commonly fail. If that's your issue the temperature control actuator is the one failing & in a dual zone setup the driver & passenger side each has one

If the pipe isn't very cold then your orifice tube likely needs to be replaced, they're cheap & easy to change but the freon has to be evacuated

 

[LsHart]

If rear are is blowing cold then the system is working. Manual hvac module? Or digital?