I have a 2003 Tahoe with rear air. I just replaced the orifice tube and recharged the system. The front vents are putting out about 64° but the rear is putting out about 56°. Any ideas on what would cause a difference like that.

Back story: I replaced the compressor about 2-3 yrs ago and everything has been fine until I did some work on a friends A/C, and my wife decided her A/C wasn't cold enough. I attempted to add some Nu Calgon A/C EZ seal (the product I added to our friends A/C) and appearantly sealed the orifice tube in the process. I opened the system, replaced the tube, pulled vacuum and recharged. Now there is a temp difference.

 

It sounds like you have had some fun with your A/C system. It is unfortunate tat your orifice tube was plugged. Since the Suburban uses a two HVAC systems, it is possible that your first repair may also have plugged the rear expansion valve. I have attached a video that you may want to refer to.

Good luck with your A/C repair.

 

As a sanity check you might want to disconnect the heater hose from the front core to make sure its not heat blending in falsely indicating warmer air... it could be the blend door(s) leaking hot air into the cold air...

 

Thanks for the input. I'm not sure this is my issues, as the rear is colder than the front, but the video was helpful. I did not realize that the rear was and expansion valve, not a tube. I am NOT an A/C tech, but my understanding is that an expansion valve is often more effective than an orifice tube. Also, if I understand correctly, orifice tube size can be sensitive to climate (ambient temp, humidity, and barometric pressure). The simple fact that the front and rear work on different components could cause a difference in temps.

Any Input?

 

Now that's a thought.... Especially considering the rear heat on this Tahoe has not worked since we bought it, so would likely not be affected by blend, AND a blend issue in the front would be localized to those vent. Thanks.

 

Can anyone confirm what is an acceptable temp at the vents before you need to investigate a problem with the system? I was expecting at least 60°