Chevelle Tech - View Single Post - r134a numbers with stock Condenser & replacement POA
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post #18 of (permalink) Old Aug 14th, 19, 4:58 PM Thread Starter
Tech Team
Join Date: Jan 2011
Location: Los Angeles
Posts: 313
Re: r134a numbers with stock Condenser & replacement POA

Originally Posted by DUTCH MAX HEADWORK View Post
We're not going to get an accurate pressure reading with the car in the garage. We need a steady ambient airflow through the cond to get the info we need. Also, starting the system from a heat-soaked state won't help us either. The engine needs to be running and temps and pressures stabilized to get numbers we can rely on.

Do you need to go into the suitcase to do any cleaning or work? Sort of bummed if the answer is yes, because I would like to pull the evap and flush it along with the rest of the system if you decide to install new parts. Starting from scratch will allow accurate oil levels in the system. Compressor, drier and txv valves are never flushed.

Your compressor is outputting necessary pressures. I would pull it if you install new parts, drain and measure the oil in a pan with a paper towel in the bottom. Check for metal debris. Spin the input shaft to remove all the oil, then refill. If you are not seeing metal flake in the oil, not hearing strange noises or seeing oily buildup around the input shaft your compressor is probably fine.

Lack of cooling can be caused by moisture in the system. Replacing the drier is a must when opening the system. If the system was open for any length of time, it's probably got a lot of moisture and contaminants in the system. Don't uncap your drier until you are ready to evacuate the system.

The sight glass looks ok, 134a is a greenish cloudy color. You can tell if the oil is streaking on the glass, I don't see it in yours but I'm not seeing the realtime flow. The sight glass on 134 will usually still show some bubbles on a properly charged system. You'll almost always see a rush of bubbles when the compressor kicks in.

TXVvalve, yeah I would replace that if the system gets opened to change out the cond.

If you want to peak the current system, we'll need some accurate numbers with the system stabilized, engine at 1500rpm and a good consistent flow of air through the cond with an accurate ambient temp reading.
Hi Al, thanks for your help. I decided to throw money at it. I ordered a new parallel flow condenser, new evaporator, & new expansion valve from Original air. In addition, I know my compressor has not been treated right the last 14 years - exposed to air, leaks in the old POA eliminator valve (which I had to replace) Never evacuated, etc... It is a March P411 compressor, so, I will not take a chance, and I will also order a new one.

The suitcase was cleaned out when the engine bay was painted. In addition, I cleaned it out again, and re-sealed it well when I changed the squirrel cage fan motor. The evaporator looked good. I do not plan to mess with the suitcase.

So the plan is - new March P411 compressor, new parallel flow compressor, new expansion valve, new dryer. Let me know if you have any other recommendations. When I get the parts, I will resurrect this thread so you can follow. Thanks.

1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
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