expansion valve help

[dieseldaisy]

I appreciate everyone's input! if anyone has anymore suggestions please let me know!
Joe

[dieseldaisy]

so here is a odd question but ....... should you shut your ac off prior to shutting your vehicle off? I have heard through the years you should shut the system off a few min before the vehicle? is it a myth? does it really matter?
thanks

[Cusser]

so here is a odd question but ....... should you shut your ac off prior to shutting your vehicle off? I have heard through the years you should shut the system off a few min before the vehicle? is it a myth? does it really matter?
thanks

1. When you shut off the AC manually, the compressor shuts off and refrigerant stops flowing. The blower motor over the evaporator may or may not still blow, depending on what control you used to "shut off" the system.

2. When you shut off the engine with AC still on, the compressor shuts off and refrigerant stops flowing, and the blower motor stops blowing. My estimate is that over 99% of all drivers do it this way.

3. When starting up, voltage is directed away from the AC system anyway, so really doesn't matter whether the AC was shut off before starting.

[Dougflas]

I have to disagree. If you shut it down a few minutes before shutting down the vehicle, you will give the evaporator time to let the condensate run off. This will help eliminate the odors evaporators put off. GM had a problem with this years ago and the fix was a kit that allowed the blower motor to run after shutting down the vehicle. Nowadays, I don't think anyone shuts the AC down before hand; I don't do it myself but I should.

[GM Tech]

It was called an "afterblow module"...ran 1 minute in ten minute period for up to ten times. Many folks complained their blower would not shut down- afraid their battery would die.

[Jag987]

Any chance that the water sitting on the evaporator could cause it to rust and leak? I have replaced more evaporators this year than any other year and have been wondering this.
Thanks

[dieseldaisy]

so I'm at a auto business. they say they think I have a leak to. I asked them if they knew how much 134 I had they didn't check but say it's def not full? how can they tell? today is a cool day so it's blowing 45 degrees but they say it should be 38 degrees the rest of the system checks out.

what is everyone's suggestion he want 250 to evacuate vacuum and fill.

I really want to know how much is in there. should I just try and put another 12 oz in and see what it does? I know I put in one can already nothing changed except the pressure did go up to 35psi on the low side. he is putting dye in it. I don't want to over fill it but geez I can buy a can of 134 for 5 bucks!

[Dougflas]

If you're handy. you can do this yourself. You can rent or borrow the vacuum pump and a set of gauges from Auto Zone. If this will be a one time mission, fine. If not, you can buy a pump and decent set of gauges from this site's sponsor.

[dieseldaisy]

I am pretty handy i actually used a set of gauges already to get my low and high pressures and used it to add a can .

I guess I'm confused about the vacuum because I thought if I vac it where does the freon that is in the system go? I thought you needed to evacuate it some how using a different machine then vacuum it then fill but I have no way to weigh what is going in?

[mk378]

A vacuum pump is used only when the system pressure is already zero to take the air out of the lines and leave a vacuum to be filled with refrigerant. It is a different kind of machine which will recover the refrigerant and save it in a tank. By weighing that tank before and after you can tell how much refrigerant was in the car. Most of the professional systems integrate a recovery pump and vacuum pump within the same box so it is only necessary to connect that one unit to the car for complete service.

Suggest you look for a different shop that actually has a recovery machine, they shouldn't charge anywhere near $250 to use it.