Background: System was converted to r-134 a few years back. Basically, the only thing that is still original is the condenser. I had a similar situation last year and I took it to an A/C mechanic (not MB) to check the A/C readings. He did empty, vacuum and recharged the system. It worked for a while. However, this is the present situation:
1) Hot air from the vents.
2) Compressor is turning.
3) Auxiliriary fan is not working. Jumped pressure switch and high temperature switch and the fan worked.
4) Readings from A/C gauges from Autozone today on a 90 degree Florida day: High side 150 and low side 80 with the A/C off. With the A/C system on, high side 150 and low side 115.

Based on searching this site, I thought it was low on r-134 but now, I suspect a restriction on the low side. Expansion valve, a/c dryer, ?

Any leads/suggestions?

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J.H.
'86 300E