99 obs ac only works while at idle?

[bigbuddy2500]

I recently replaced my entire ac system, followed the fsm that I found on this site, the compressor came prefilled and sealed with oem oil.

Its been working great for about 3 weeks, last night and this morning the ac will only blow cold when I'm at idle, if I get on the highway it blows warm air. The only thing I can think of is I installed a variable orfice tube instead of a fixed one. It's an ht6 system, would that cause this problem?

Also it does make a odd noise from the evap core to condensor kinda like a squealing liquid noise. I'll try record it and upload a video

 

[bigbuddy2500]

Bump?

 

[bigbuddy2500]

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Here's a quick video

 

[kennythewelder]

There could be a small piece of trash hung up on the orfice tube. How well did you flush out the system before pulling a vacuum, and filling with freon? The pressures must be checked at rest, at idle, and at speed. All of this has to be read on both high and low sides, and you must use an ambient temp chart to get the correct readings. It may be as simple as the system being a little low on freon, or a complex as trash in the orfice tube, in that case, the system has to be discharged, and then flushed out again, the replace the orfice tube, before closing the system up again, pulling a vacuum again, and recharging with new freon, again.

 

[bigbuddy2500]

The cycling switch, and low pressure switch are original, everything else is new, evap core, condenser, dryer/acuu, compressor and all the lines and high pressure cut off switch. I pulled vacuum for 2 hours and then I charged it with freon. The compressor came prefilled. As the system was dry I added 3.5 oz pag150 to the accumulator, 3.5 oz to the evap core and 1oz to the condensor and 2lbs of freon. I won't have time to evac the system and change tubes till Saturday, if I have to flush what do yall recommend for the flush?

 

[bigbuddy2500]

Update, finally had time to do it Sunday, evac the system, I had about 32oz in it, so I was low about 4oz. After swapping the orfice tube, I vacuumed the system, and it held, so I filled it. I think what I did wrong the first time is that I didn't purge the yellow line after taking it off the pump. This time I purged it till freon came out, and filled the system back up. So far no problems.