Finally got the fresh 5sfe in the car and it runs great. A/c worked fine until this evening (105 deg and about 130 in the car). Started it up and turned on the a/c and when it started blowing cold hopped out. When I got back to it it's just blowing hot. Checked the high and low pressure lines at the compressor and they were the same temperature. The a/c clutch IS engaged.I shut it off and after a bit checked the low side and got a VERY low indication so I figured it must have sprung a leak and the compressor was still engaged because something else must be stuck (relay cutout). Then I checked the high side and found out where all the freon and pressure is. Would the high pressure bypass valve that's inside the accumulator cause this if it was tripped or do I have a system blockage somewhere?

 

There is a site glass on top of the receiver/dryer allowing viewing of the freon during AC operation.

When the compressor is off the fluid should be clear.

When the compressor kicks in bubbles will form then the fluid should become clear.

Upon compressor shut down the fluid will again form bubbles then become clear.

If the fluid become too low a pressure switch will not allow the compressor to start. There is a green light on the AC switch, the light will start blinking if the compressor is not starting up.

If the system ran OK before the engine swap it may be just low on freon. Freon can leak out over time, the system is not perfectly sealed.

The cheapest first step would be to buy a refill can system having a gauge on it. Follow the directions to install the hose on the LOW pressure side and check pressure.

Low side pressure should be 22-36 psi depending on the air temp, compressor working, engine at 1500 rpm.

The gauge has a scale of air temp vrs pressure. If the pressure is low, SLOWLY add freon until it comes up the required pressure.

Or buy or rent a AC gauge set. This will allow a more accurate check of the system.

 

Went out today and picked up a can of freon. Got back home and the a/c is working fine again. If anything it is colder than it should be for sitting still. I think it may be overcharged and something tripped in the system to bypass the pressure. It also may be moisture froze at the evaporation point and blocked the line till it defrosted. New car to me so I don't have history on it. I'll keep plugging away but will get the gauge set to check low and high sides. Thanks