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-   -   cant get the ac working after engine install (http://www.hotrodders.com/forum/cant-get-ac-working-after-engine-install-223595.html)

briansansone 09-01-2012 02:29 PM

cant get the ac working after engine install
 
Well I'm trying to get my ac going again after adding a new engine.
I flushed the lines. added new oil, o-rings, seals, and an in-line filter.
I started adding refrigerant after evacuating the system, and the pressures were all over the place. too high, too low...... One minute the low side is 20 psi while the high jumps to almost 400. Then i'll turn it off, restart and the pressure is closer to normal. resting pressure is too low one minute and too high the next. Last check, which seems somewhat stable

low side at @50
High side at @ 150
resting pressure @ 125

Bad Compressor??

I am no ac pro...

grandpa01 09-01-2012 02:38 PM

How much refrigerant and are these pressures at idle. Did you replace the drier?

briansansone 09-01-2012 02:53 PM

yes the pressures are at idle speed.
125 psi with the engine off and the system equalized.
I replaced the accumulator.

The system calls for 68 oz. I have about 60 in there, and there is no change in temp. Its a van with rear ac.

The line just after the orifice tube at the evap inlet is freezing. but at the evap outlet it is super hot.

grandpa01 09-01-2012 03:18 PM

Is the orifice tube new?

briansansone 09-01-2012 03:27 PM

yes. and the sytem was pretty clean even before i flushed it

LATECH 09-01-2012 04:04 PM

Compressor is fine , as it is making 400 psi plus. Dont do that too much it wont be fine:spank:
Icing at the low side of the orifice means the orifice is plugged, or is way to small. What color did you put in?
Also, it sounds like the expansion valve in the rear (orifice if on an aerostar) is also plugged or not responding correctly.
Did you check / flush the rear lines and check the rear TVX device?

briansansone 09-01-2012 04:14 PM

the tube I put in was white. visually it looked the same. its definitely icing on the low side. and it will burn you at the outlet of the evap. I flushed everything except the expansion valve and rear condenser assembly. its ridiculously difficult to disassemble. I even considered bypassing the rear system.

LATECH 09-01-2012 04:26 PM

White is the largest of tubes available at .072" inches.
The problem is most likely at the rear expansion valve. It is probably blocked or plugged, or is defective and is closed off, not letting freon pass, causing high side readings to be high, and low side to be low, and everything inbetween.
I would have to suggest opening up the rear at the expansion valve , both lines, and flush the lines, and replace the valve or orifice at the rear.

johnnyg 09-01-2012 04:36 PM

Did you vacuum the system?

briansansone 09-01-2012 04:37 PM

I just checked again.

resting pressure now about 85

idle= 25 low 225 high
after 5 minutes= 30 low 315 high.

its not icing any more.

briansansone 09-01-2012 04:39 PM

yes i vacuumed the system for about 45 minutes. then i let it sit for an hour.
the gauges stayed at -30 vacuum.

briansansone 09-01-2012 04:59 PM

Quote:

Originally Posted by LATECH (Post 1587603)
White is the largest of tubes available at .072" inches.
The problem is most likely at the rear expansion valve. It is probably blocked or plugged, or is defective and is closed off, not letting freon pass, causing high side readings to be high, and low side to be low, and everything inbetween.
I would have to suggest opening up the rear at the expansion valve , both lines, and flush the lines, and replace the valve or orifice at the rear.



thats what i was afraid of. half the interior has to com out to get to the expansion valve.

LATECH 09-01-2012 04:59 PM

30-315 is still not right for a dual system. Do you have good airflow across the condensor? Cooling Fans working well?
30-315 still sounds like rear system not working right.
pressures should be more like 45-225 after system stabilizes (running for 5 minutes with recirculate on).

briansansone 09-01-2012 05:11 PM

actually, i have an electric cooling fan pulling air. its about 85 degrees here right now.

i'll probably take it to an ac shop tuesday. it will have to be emptied before i can unearth the expansion valve.

LATECH 09-01-2012 05:18 PM

Be sure the temp/blend door is closed and not heating up the refrigerated air as it passes through the ductwork. If all is well there then you will need to take a good hard look at the rear system.
I have found that the rear system tends to gather debris as the hoses are at the lowest point in the system, also expansion valves can stick, or fail for no apparent reason.


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