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Success! ........I hope

Cletis too on Wed August 22, 2007 9:04 PM User is offline

Year: 1956
Make: Chevrolet
Model: 3100
Engine Size: 350
Refrigerant Type: r134
Ambient Temp: 87
Pressure Low: 5
Pressure High: 160

Thanks to the great people on this forum, I have my new system up and running. The evaporator is a Hotrod Air unit. I'm running a V4 compressor. I evacuated the system for 30 minutes then held it in vaccuum for another 45. I charged it with 30 ounces of R134. The outlet temp is 42 degrees with the blower on medium.

Question: Are these pressure readings within specs? The evaporator kit instructions give no clue.

Thanks again to all the guys who helped me and to the forum owners for providing this. Even though I turned wrenches on military aircraft for over 36 years, I was clueless about this installation.

Chick on Wed August 22, 2007 9:20 PM User is offlineView users profile

Are you sure the guages are calibrated, or zero'ed in ?? Pressures look a bit low..But you are almost there... I know it's cold, but without the right amount in there, you won't move the oil around and that R4 can get a little noisy with enough oil.. Add a couple ounces at a time until you get the high side up around 175psi (with zero'ed guages) and you can go as high as 195-200psi on the high side at that ambient temp....That will bring the low side up a little too..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Cletis too on Wed August 22, 2007 10:16 PM User is offline

Thanks for your help, Chick.

I added a partial can with maybe 6-8 oz to it and it brought the high side up to almost 170. Low side stayed about the same. The gauges are parts store loaners but appear to be good quality and are on zero when emptied. Do you think aai should get some more refrigerant tommorow and try to bring the high side up more? Ambient temp is now about 83.

Thanks again.

Chick on Wed August 22, 2007 10:26 PM User is offlineView users profile

Not sure what system you have..Is it an O tube accumulator, or expansion valve drier type?? You should have the evap inlet and outlet the same temp..Outlet can be a little colder..If it's warmer than the inlet, you need to add more..Once they are the same temp, you're done..Let the system equalize betwen refrigerant charges..You can bring the high side up to around 2.2 to 2.5 times the ambient temp, provided you have good air flow over the condenser..(Fans working)

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

Cletis too on Thu August 23, 2007 6:00 PM User is offline

Chick, when you say the evap inlet and outlet should be the same temp I assume you mean the refrigerant tubes, not the air.

By the way, it has an expansion valve and drier.

Edited: Thu August 23, 2007 at 6:02 PM by Cletis too

Chick on Thu August 23, 2007 6:14 PM User is offlineView users profile

If you can feel the outlet of the expansion valve (cold end) and the outlet of the suction line from evaporator, it should be close.. Expansion valves are much more efficient than O tube systems, which this method works best on.. But make sure the suction line is cold back to the compressor..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

bohica2xo on Thu August 23, 2007 8:07 PM User is offline

Cletis:

Open both cab doors, and set the evaporator fan to it's highest speed.

Run the engine @ 2000 rpm for 5 minute to stabilize the system, and record the pressures while @ 2000 engine rpm. Record the vent temp & ambient temp.

Let us know how it does at full load.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Cletis too on Thu August 23, 2007 9:22 PM User is offline

Well heck. I drove it to town, about 15 miles, to take the gauges and pump back. By the time I got there she was blowing hot air. So I brought the gauges back.

This afternoon, before the trip, I added more r134 and got the high side to 235 and low to 7. Ambient temp was 94 and vent temp was 39. I was happy with that.

When I got back from town I read bohicas post and set it up that way. It's now reading about 170 high and a slight negative low. Ambient temp 89 and vent temp 95. I've tried reading the inlet and outlet temps with an infrared thermometer but get varying readings. The expansion valve feels cooler to the touch than the line going into it.

What do I do now? Shoot it?

iceman2555 on Thu August 23, 2007 9:45 PM User is offlineView users profile

It is surprising that a V4 (?) compressor is being used in this application. HotRod list a Sanden for this application. However, since their website does not have a tech section....pardon our dust...the site is being prepared.......okay!!!, a quick glimpse of Vintage Air did shed some light on this system. They require a 1.8 lb for their 134a system and state pressures of 6-7psi on low side and upward to 235psi on the high side. These low side pressures quoted a a bit strange...but then they should know their products.
Suggest to check with HotRod and obtain some recharge specs, lube and refrigerant for your system. It is important to know the correct amount of refrigerant the system is necessary for the design of this system.
The following is a excerpt from the Vintage Air web site....some interesting ideas concerning evap freezing.
Internal freeze up occurs when there is too much moisture inside the system. The symptoms of internal freeze up often surface after extended highway driving. The volume of air stays constant, but the temperature of the air gradually rises. When this freezing occurs the low side pressure will drop, eventually going into a vacuum. At this point, the system should be checked by a professional who will evacuate the system and change the drier.
See if you can obtain more info from the kit mfg'er and post.
Good luck!!!!

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

Cletis too on Fri August 24, 2007 1:51 AM User is offline

Iceman, the reason I'm using this compressor is it came with the truck. It is fresh re-built and also a new condenser came with it. Both sealed and in the box. There was also an aftermarket evaporator of unknown brand installed but the ports had been open for who knows how long so I bought the Hotrod Air evaporator kit. I also used their hose kit and dryer. Yes, their support leaves a lot to be desired. Their installation instructions do too.

Sounds like you are right about it being a freeze up. From what I've read, I thought the evacuation process should have removed all the moisture. Should I have kept the pump on longer? Do you think I've ruined the new dryer?

Tomorrow afternoon I'll put the gauges on it again and see if it thawed out but I think it's time for me to take it to a shop.

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