Ac gurus need a quick answer

[BrianX128]

So I just finished up putting a cold master under dash ac system in my idi. It works great and the psi stays at 30 while its running but the dryer never gets cold to the touch.

Its blowing super cold air and the evaporator is leaking water out like crazy so its doing everything else right. Am I safe to take it for a test drive do you think?

I also only put 1 and 1/2 cans of r134 a in the system with a couple extra ounces of pag46 even though it said it had enough oil in the compressor.

 

[riphip]

Dryer or Accumulator. Dryer is on high side liquid after condenser / accumulator sweats because it is on the low side evaporator where vapor returns to compressor.

Give it some throttle to see how far below 30 it drops at higher rpm.

 

[BrianX128]

This. It says it's the dryer in the directions. The system doesnt have anything else here I'll post up the diagram from the bad directions also.

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[riphip]

Dryer will not sweat. The eye in the top should go from cloudy to clear when refrigerant is right. R12 or 134A

 

[BrianX128]

Yeah the sightglass gets cloudy

 

[riphip]

A little more until clear. RPMs about 1200. You can watch it flow. Probably doesn't need much more.

 

[BrianX128]

It runs for 15 20 seconds and shuts off for 15 or 20.. I'm at Walmart getting two more cans of pure 134 but the good sign is it's not loosing pressure after being on the whole trip

 

[riphip]

You did vacuum the system??

 

[Thewespaul]

I agree it sounds like you need more refrigerant

 

[BrianX128]

Well I put the latest can in it now has 2 and a half 12 ounce cans. It runs for a minute straight and then stays off for 15 to 20 seconds and runs another minute.

I'm wondering if the old sealed compressor I had runs at a different pressure than the switch they provided. It holds at 25psi while running for the entire minute and never drops below 25 even when it kicks off. The guy I talked to at the place said I could use this old nippondenso compressor instead of theirs if it didnt fit from the kit as long as I vacuumed the system which I did but I'm wondering what would happen if I force the compressor to stay on for more than a minute.

It's by far the coldest air I've ever had from an ac system for the minute it runs and it still feels cold the 20 seconds it's off. It also is only 65 tonight so I'm wondering if the evap box has a thermostat.

I know I should have used their compressor but it flat out doesn't fit and I know this compressor works. The old R12 compressor on my other idi has powered a 134a system for 3 years now without a single charge extra. Guess I'll have to try it in the heat and see what happens. Could always fab a mount for their compressor but it would be rough.

 

[riphip]

Cycling to keep from frosting evaporator. If eye is clear, it is full. once you are moving air across the condenser, it may not cycle as much but may also get colder inside. I keep a digital thermometer in my vent just for checks. I like the dryer/expansion valve system better than the accumulator. Watch that eye & you can tell when it is full or has leaked. easy to add refrigerant if needed.
You do have the hose clamps on backwards but leave for now & enjoy!!!

 

[BrianX128]

I learned something with it on the way to work today, at higher than 1500 rpm it cycles on for 40 seconds off for 20 but at idle and low rpm it will stay on for over two minutes and off for 20 seconds.

Would there be any harm in running a jumper to the condenser off a toggle in the cab to force it on? Maybe not permanently but to see if the evap freezes over or the low side pressure falls below 25?

 

[gnathv]

At 25 psi 134 is 28.7 degrees. With air flow over the condenser most likely your pressure is less and causing it to cycle to prevent freeze up. Is your sight glas clear at a fast idle and are you watching for a while to see if bubbles are cycling through?

 

[BrianX128]

I'll have to check again. If it's not is my pressure still too low? It seems like adding 134 now isn't raising the pressure anymore even with the compressor cycling it just doesn't seem to want to go over 25. Granted I've only put 2 and a half cans in and the half can may have been more like 1/4 of a can so say 26-28oz.

 

[BrianX128]

Maybe I just don't have enough coolant. I just drove it home and man it keeps the cab comfortable first run after it sat in the 83 sun all day it ran for 7 minutes straight. Then it started cycling on for a minute off for 20 seconds. Yet at idle it will run for almost 3 minutes straight.

Not sure. It's ok as is but I don't want to wear the compressor out cycling it yet it is an old r12 compressor. Wish the stupid one that came in the kit fit like its supposed to..