I am about to charge my ac system and was wondering the high and low side I should expect for the hot 110 degree weather here in AZ. I found the low side from my Internet searches to be at 45 lbs for about 90 degree weather but I know when it's 20 degrees hotter at 110 it should be even higher.

Okay so for 110 degree heat in driveway so there is not as good circulation as there is while I am driving, what should the high and low side on the gauges be? At 1200 rpm.

Thanks guys!

Doing my f-250 truck first. It just got a new compressor,dryer, etc.

You need pull a vaccuum on the system before you can add anything. In 110 heat you dont want to go any higher 65 on the gauge period.

....Well .... you should also ask a Ford dealership what the low and high side pressures should be...even maybe your local parts store,AC supplier,and AC shop., IF YOU OVER PRESSURE the AC system, nasty things happen. Thats why their is a ......DANGER....reading on the GUAGES you should be using......REPEAT.....Their is a ...DANGER ....reading on the guages you should be using. The best technique for recharging the system seems to be Early in the morning when the temperatures are the coolest....You may wish to use a little dye in in the system to ensure your new components are tight and sealed., and possably a "conditioner" (a lubricant) which can extend the AC systems life....YOUR quality LOCAL PARTS SUPPLIER will have everything you need....P.S.freon does not exist anymore ,for cars....you'll be using....R-134.

you can read alot about the a/c system condition by the high and low differential readings, but it looks like you covered all the bases.

on a system without info. on the charge amount needed you can get a fairly accurate fill by watching the frost line move up to the condenser (and watching the high side pressure). kind of like the old systems using a sight glass to visually watch for the charge to change from bubbles to solid.

you have an orface tube in there so ideally your 1200 rpm should be constant with other rpm's. note: did you change your orface tube? same color?

the clutch cycles out when the pressure is high out of range. some are low/high. by using the above frost fill method first, a cool trick i used to do was tune the pressure cut out switch. use a temp gauge in the vent for temp. varificaion then remove the pressure switch electrical plug, with a small flat screw driver turn in or out just a little, plug back in and check temp.s. this alters + or - the cycle time, raising or lowering high side pressures. all part of balancing the orface tube/evaporator size to the pressure/cycle time

that was long huh? i just love a/c crap though

On the 914 is the condensor the right size for 134a? It takes a larger condensor to use 134a than it did for r12. You might want to read up on one of the aftermarket ac suppliers sites on the size difference. I will duplicate the suby size in my 914 probably.

The good thing is the 914 is so small it should be easy to cool with suby ac stuff.

This might help some.
http://www.iceac.com/germanproducts.html Course you can take the cfc 12 bs however you want. I personally think it was a ploy to force a new chemical on the market that a big price could be placed on.

I'm a little concerned about the evaporator size of the old ac units that came in the 914 but I will probably just use one anyway to see how it goes. It's 105 at the most usually here.

I put a 64 ac unit converted to 12v in my bug in 69 and it was a sedan converted into a pickup so I only used 1 of the undermotor condensors in the front in the lower sparetire well with a sucker fan and it worked good with r12 but I'm sure it wuldn't have been as good with 134a. I took it to the local vw dealer to check out and fill and they thought it was good to go. man it had a ton of extra pressure controls on it.

It's been a while:

Starting with your truck, I'd make 100% sure what's in the system, R-12, Freon, 134 etc.

Before hooking up gauges and trying to figure out what your head pressure is, I'd take the advice someone posted above. Spend the $50 and have a shop evac it, put a vac on it and test for leaks. You can take the truck back with the system empty at that point if you like and just fill from there. Use one of those digital scales and just fill by factory specs by wieght of refer.

To really max out the performance of your system, you really need to know what the super heat and super cool both are after the intial charge. BUT, if you do the above, that's as good as it was delivered off the lot when new, so all should be cool, literally!

The purpose of pulling a vac is not only for testing purposes, but so the R134 has someplace to go. If you try to put in anything w/o doing a vac you have the atmosphere that you have already trapped in there when replaceing componets. Also make sure to add the proper oil and amount to the componets you replaced. You typically need to drain the oil out into a measuring device to see how much to put back in.

You haven't said if this was a conversion to R134, if it is you use and 80% of R134 of what was marked for R12.(ie: if sticker says 2lb of R12 then use 1.6lb of R134)

That's a goog point, my comment was assuming you'd be putting back in the same type of refer you removed (Properly reclaimed of course).