a.c. code 448

[Guest kennyw]

cleared codes. a.c. compressor is now supposed to run. At least for a short time. Compressor does not engage. Thoughts are now it is not receiving power at any time? Padgett mentions code 447. What is the 448? Ken

[Ronnie]

Try disconnecting the battery to clear the codes. B448= Very low refrigerant pressure.

[padgett]

446 is low pressure (can be cleared)

447 is very low pressure (need to disconnect battery to clear)

448 the same as 447 but may be related to BI08 (do not have a low system to check)

[Guest Mc_Reatta]

B 448 indicates that the output of the low pressure switch (value of B 108 in data) was low for more than 3 minutes. This is different from B 447 which can also be set from the low temp sensor as well as the switch.

This indicates a hard fault between the switch and the BCM.

Possible causes:

Almost no freon in system (pressure lower than 15 psi at all times.

Low pressure switch is defective (remains open even if more than 15 psi present)

No power to switch (10 AMP A/C fuse blown or wire / connector damaged),

12 volt Signal from switch not getting to BCM (broken connector / wire)

Since it takes 3 minutes for this code to be set, you probably have another issue as well preventing the compressor from coming on right after you reset the codes.

Have you checked fuses, relay and connector at the compressor clutch too?

[Guest kennyw]

Reatta has been sitting for 6 to 9 months because of no A.C. Had both other cars in for hail damage repair. Why I had to use the Reatta for 2 days. On battery tender w/battery disconnected. I cleared codes on the touch screen as per one post. Disconnecting the battery would not have helped as that is where I started. I changed the sensor that does not let the freon out. Still no go. I will look at the fuse tomorrow. I still think no power to the compressor for what ever reason. When this all started I had a hard time getting one can in the system. Compressor was not running back then either. Why I believe the system is not low.... Driving it for 2 days made me remember why I bought it 10+ years ago. If the A.C. worked I might even think of painting it. With 161,000 0n the clock we all know it isn't worth much. I have fixed 80 percent of the usual problems over the years. Even 2 crank sensors. Even had both 110-inverters working at the same time. Nice to see everything lit up. Even had the light show working at one time. Got the Avalanche back today. Will either get the A.C. working and use it sometimes or back on the battery tender. To good to junk and not worth the cost of both A.C. and paint.....Ken

[padgett]

ES06 should cycle the a/c clutch if fuse 19 is good and the LO PRESSURE SWITCH is closed. See the circuit diagram in section 1C chart 1 of the FSM.