Chevrolet Repair: 99 YUKON/ REAR A/C ONLY WORKS ON HIGH, gmc yukon, chevy tahoe

Question
QUESTION: HI WAYNE, I HAVE A 99 GMC YUKON 4X4. THIS IS THE SAME AS A CHEVY TAHOE. QUESTION IS THE REAR AC FAN/ BLOWER WILL ONLY WORK ON HIGH. HEARD THIS MIGHT BE A "BLOWER RESISTOR BLOCK"? YOU THINK THIS IS IT, ANY OTHER IDEAS? WHERE WOULD THIS BE LOCATED FOR THE REAR BLOWER? IT WAS WORKING YESTERDAY THEN 10 MINS LATER IT WASN'T. I WILL SAY THAT I DID REPLACE THE SMALLER TUBE THAT GOES FROM THE REAR CONDENSER UNDER THE TRUCK & CONNECTS TO A RUBBER HOSE THAT GOES TO THE FRONT OF THE TRUCK, NOW EVEN AFTER I RECHARGED THE AC & CHECK FOR LEAKS MYSELF BY USING SOAP & WATER; THAT IT IS NOT HOLDING THE FREON. IT SEEMS TO BE ESCAPING FROM SOME WHERE BECAUSE THE AIR IS'NT COLD ANYMORE & THE COMPRESSOR KEEPS GOING ON AND OFF. ANY ADVISE? THANKS SO MUCH!

ANSWER: HEy,

 Blower resistor is located in the HVAC box.  Rear condenser?  There is only one condenser on a 99 GMC.  Once condenser on all vehicles for that matter.  Do you mean evaporator?  Have you checked the pressures with a manifold gauge set?  Did you accidently remove the orifice tube?
Wayne


---------- FOLLOW-UP ----------

QUESTION: IS THAT HVAC BOX UNDER THE DASH? THIS IS WHERE IT WILL BE FOR THE REAR BLOWER FAN? I GUESS IT'S A EVAPORATOR, IT'S LOCATED IN THE REAR OF THE TRUCH BEHIND A PANEL. ATTACHED TO THIS IS A BLOWER FAN, I ASSUME IT BLOWS THE AIR THROUGH OR ACROSS THE EVAPORATOR TO COOL THE AIR. THERE IS A SMALL/SKINNY ALUMINUM ? TUBE THAT CONNECTS TO THE EVAPORATOR THEN GOES UNDER THE TRUCK TO ATTACH TO THE RUBBER HOSE. I REPLACED THAT TUBE BECAUSE I HAD A BLOW-OUT & THE TREAD FROM THE TIRE HIT & BROKE THE TUBE IN HALF. I PUT TEFLON TAPE ON THREADS & TIGHTENED GOOD BUT SEEMS THERE IS A LEAK SOME WERE THOUGH. THANKS

Answer
Its in the rear HVAC.  What type of AC line repair did you use?  You have to use a special hose or it will permeate out.  The thin line is the high side and the thick one is the low side.  Operating pressure of the low side is anywhere from 20psi to 80psi static depending on ambient air temperature.

Wayne