Should a/c compressor cycle on/off while driving?

[xHeart]

Thank you for commenting jimmy.

Lee comment over there https://www.matthewsvolvosite.com/forums/viewtopic.php?f=1&t=62956, it says "You need to have the compressor on to get the refrigerant to flow into the system".

I am assuming idling would be adequate for this refill procedure. The clutch ON and OFF every few second has no affect on refrigerant flow from can to the system, right?

[wheelsup]

If you live near a Harbor Freight they sell gauges for roughly $45. You'll need a can tap and you can get those at most auto parts store, Amazon, etc.

Gauges $60 - 25% coupon $45 OR if you can find a coupon they are normally $44.99
http://t.harborfreight.com/ac-r134a-man ... 60806.html

Can Tap example
http://shop.advanceautoparts.com/p/inte ... 4a+can+tap
or
https://www.amazon.com/Interdynamics-DV- ... 4a+can+tap

I would suggest buying a can tap and gauges because first they are a ton easier to use than that $22 one you listed, second you can use the can tap and charging line to feed straight 134a and bleed the line without letting in air (although to be fair that little amount won't do a thing), and third if you ever want to do the evap job yourself you can suck it down using those gauges and refill for <$20 vs. >$100 at a shop.

It really isn't rocket science. Yes, you're supposed to weigh the charge, yes you're suppose to have a certain amount of cycling, you know what, charge it up till it stops cycling and blows cold and call it a day...

Once you introduce the refrigerant into the system the compressor should come on automatically. There is a way to jump the low pressure switch IIRC but it's not needed. Just turn the can sideways or upside down if the compressor doesn't come on. No, it won't hurt the compressor because our cars use an accumulator and the liquid refrigerant first goes into the accumulator, where the vapor is sucked out via a line on top (google an image of an ac accumulator). Liquid refrigerant going into the compressor is bad, on cars with a receiver dryer you can't just dump it in like that you have to keep the can upright and shake it to dispense it slowly. Sorry enough talking. Just do it already and enjoy the nice cool air.

Mine knock on wood is still going strong, the problem I had was that it was under charged, I used after market components which must have a larger capacity.

[jimmy57]

The cycling will make it go slower but if you need to use a stick on the accel pedal for a 1200-1500 rpm engine speed you will get a better gauging of cooling and the faster speed will make the low side pressure lower and the refrig will flow into system faster.
The prescribed way to evaluate a/c is always to have fast idle by all manufacturers' methods.

[xHeart]

I have manifold hooked up to low pressure port.
Engine idling, low fan, a/c ON, once turing knob presses on the low pressure schrader valve the gauge jumps to 20psi. It climbs to 32psi then the clutch stops. Once the gauge climbs to 40psi, the clutch engages back and psi drops to 32.

The clutch cycle is 5/10 sec while the gauge fluctuates between 32psi and 40psi. Ambient temp is 73º.

The cabin air feels cool.

Does A/C need charge?

[xHeart]

Now cooling, you would love it.
The humming sound is back.
I took one 12oz can to travel from 25psi to 36psi, an 11psi increase.
Is this the formula 1oz = 1psi?

[abscate]

It doesn't translate easily into ounce=pressure.

System pressure is measured at fast idle with system equilibrated, blower in high, recirc on.

[xHeart]

It doesn't translate easily into ounce=pressure.
System pressure is measured at fast idle with system equilibrated, blower in high, recirc on.

It was 25psi @ 1500rpm, fan at max, a/c ON, recirc ON, ambient in garage 76º.
Inserted thermometer at vent, needle moved to 74º.
Then connected the Autozone's R134 12oz can, turning and shaking it a little the compressor stayed ON after 5 minutes.

A 20 minutes of activity with the can, it was empty, thermometer showing 43º, and 36psi on gauge.

Pressure off the gas pedal, idling at normal rpm. Disconnected the low pressure valve connection.

The drain line is clear, I see water on the floor.

[abscate]

33degrees F of temp delta is pretty good, 40F is really the best you can get I think.

33F will be pretty comfortable unless you are in Death Valley

[matthew1]

Hey Wheelsup, do you still have this video? It's gone off Youtube for some reason.

Congrats on your successful repair, and send me good kharma points. Charging my AC is up either this weekend or next..

That's a nasty looking evap core....looks like Jimmy Hoffa might be stuck in there too..

I shot this video charging it up

[wheelsup]

Hey Wheelsup, do you still have this video? It's gone off Youtube for some reason.

Congrats on your successful repair, and send me good kharma points. Charging my AC is up either this weekend or next..

That's a nasty looking evap core....looks like Jimmy Hoffa might be stuck in there too..

I shot this video charging it up

I don't, sorry.