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A/C front vents

I have a 98 Chev van 1500 with dual a/c systems. Turning on front a/c air comes out with mild warm air, then turning on the back a/c cold air rushes out as it should. Just had the compressor charged. Mechanic thinks the front flaps are not closing all the way?? Possible fuse, front flaps stuck fuse or what?? All help appreciated.

The flaps are called blend doors and they may be controlled with electricity, cables or vacuum lines. My guess is you have vacuum lines and there is a problem there, maybe a split vacuum hose. The trick is to get to it.

If the vans are like the Suburbans and Tahoes the front system is a orfice tube system and the rear is a expansion valve system,perhaps a orfice tube replacement is all thats required.

Hi. Thanks for the reply, where is the orfice tub found?

Its going to be on one of the lines to the condensor near a threaded fitting and there will be a little dimple on the steel line. System must be discharged and sometimes they are stuck in the line (there is a puller tool)You may have to partialy remove the grill, use back-up wrenches (this means use two wrenches,one to turn and one to hold). The condensor is at the front of the vehicle,it looks like a radiator.

The location of the orifice tube is located at a line connection in which a larger line attaches to a smaller line. The orifice tube is inside the smaller line. Again, it is not a DIY job unless you have professional a/c equipment lying around your garage and the knowledge and experience to use it well.

This orifice sounds like it has more to due with the 134 stuff than the blend doors opening or closing because the rear unit or discharge vents work fine and cold??? I am not a DIY on a/c so I should take it to an a/c spec. shop or general Chevy dealer??

If your car gets dispatched to a competent AC tech it doesn’t matter if he works for thr Dealer or a speciality shop. Give the speciality shop a look over and get a feeling about how they operate. When you speak to the Manager/Owner do you get a sense of competency? can you speak to the mechanic who is actually going to work on your car? Your problem could turn into a expensive/difficult one so you don’t want someone who is still learning basics to get his hands on your car.

In brief I vote for the speciality shop if they pass the “smell” test.

thanks for the advice. Could an orifice effect the operation of the blending doors? Do you know if the blending doors are vacuum or elect?

The orifice tube does not effect the blend doors at all, it is sort of like a filter for the refrigerant. It also serves to slow down the flow of the stuff and create some back pressure, so to speak. It will tend to catch any junk in the lines, like dirt or pieces of seals, etc. and get clogged up, affecting the performance of your a/c. This could account for warm front air on a dual system, and could be hard to pick up on since the pressures probably look normal due to the rear working normally. It is certainly worth a try to replace it. Replacing the orifice tube is probably the single cheapest a/c repair you can have done.

Hi. Thank you Mark for all the info. It looks like I will start with the orifice. I suppose the system will have to be recharged after replacement of the orifice?