All new A/C system--> big problems. Help??

[Vettepilot]

Restoring a 1994 GMC K1500 with 5.7 V/8. I installed virtually ALL new A/C system components, except the evaporator. I thoroughly flushed the evaporator, and pressure tested it for leaks. (None)

Vacuumed the system down for one hour plus, and then the system held the vacuum overnight with vacuum pump disconnected. I then started to charge the system as normal. Often times, if I work quickly, I can get enough freon into the system just from the vacuum, that the compressor will kick in and I don't need to bypass the pressure switch. In this case however, there was an electrical problem and the compressor didn't turn on. The system took a little under two cans on it's own, (about 20 ounces +/-) without the compressor running. Capacity is 32 oz. System calls for 8 oz total oil. New compressor came with 7 oz so I added 1 oz to new accumulator.

When I finished fussing with the electrical problem and got back to tending the gauges, things were all out of whack. The low side is pegged high, and when the compressor is on, the high side quickly (in about ~5 seconds) goes to emergency cut off at 450 psi plus, then the safety switch kicks in and turns the compressor off. Static, engine off pressures are Low side = pegged, High side = 125 psi.

What's wrong here, and what's the fix???

Thanks!
Vettepilot

 

[Dropped88]

I've seen that before and this is going sound crazy but check lines at the condenser I've seen those installed backwards cause they used same fitting for both connections

 

[Spareparts]

Possibly the expansion valve?

 

[pressureangle]

Check for kinked high pressure hose...I got nothin' else.

 

[GoToGuy]

Over pressure switch " opens " interrupting power to comp clutch.
Right now it's over serviced.
Reinspect to ensure all lines are routed correctly.
You don't have to jump the low press shutoff switch. As you fill with the first " can " , the pressure will rise , closing the the low press switch and compressor will start running.
What electric problem?
Recheck all work, ensure system plumbing, and orifice was correctly installed?

 

[Vettepilot]

I've seen that before and this is going sound crazy but check lines at the condenser I've seen those installed backwards cause they used same fitting for both connections

Holy Smokes!! You might be on to something! I had a god awful fight getting those lines aligned and hooked up on the new condensor!! But now I can't remember which line had the orifice tube in it to check.

???

Vettepilot

 

[PlayingWithTBI]

The orifice tube goes between the condenser and the evaporator.

 

[Vettepilot]

I've seen that before and this is going sound crazy but check lines at the condenser I've seen those installed backwards cause they used same fitting for both connections

Holy Smokes!! You might be on to something! I had a god awful fight getting those connections lined up and hooked! Crap, now I don't remember which tube the orifice tube was in to go check, but from what I can see without removing the grill right now, they might be reversed. So this would lock pressure in and cause this problem?

THANKS! GREAT CATCH!

Vettepilot

 

[Vettepilot]

Sorry for double post--> computer hickup.

Vettepilot

 

[Vettepilot]

@Dropped88 you nailed it!! That was the problem!! Thank you so much for your post and help!

While I did check the new orifice tube while putting this all together, later when I was fighting hooking up the lines I didn't think about it because I'm kind of used to the O-tube being back near the firewall. The new lines were not fitting up well at all, and in trying to get them properly bent and aligned and hooked up, YEP, I got them backwards and consequently the O-tube not at the right point in the system.

GOOD CATCH Dropped88!! Thanks again. You know, I researched the problem for hours, and posted in no less than five forums. You were the only one to nail it. I'm embarrassed here, but way happy to find the problem. (Note that some said "check the plumbing" which was also correct, but he nailed it dead on.)

I was tearing my hair out, so I can't thank you enough! (Hey, been doing this mechanic stuff for 55 years, so I don't have much hair left to pull out!)

God, now I've got to dig into malfunctioning HVAC doors. Probably all three actuators. I really, really hate interior and dash work...

THANKS!!
Vettepilot