dporsche74

Just got a 1990 964 C4 Hot rod

First .. the A/C was not working when i bought it up and heat was working fine

So...I got a new a/c condenser.. new ballast resistor
.. new R14 relay's .
I took it to the shop for the R134 conversion.. they tested it and filled it
pressure is good. high and low side.

The strange part is... With the R14 relay installed the a/c doesnt get cold.
the condenser fan cycling on and off .. Heat willl not work . (blower cycles on and off and no heat) . I see the mixture servo working back and forth cycling and no heat ) Oil cooler fan is doing the same thing on off cycle..

So...I pull the R14 relay out.. leave it empty .. the A/C is working nice and cold
Heat is working.. get hot and fresh air working normal . oil temp temp is low

Everything works like it should and working well
the only thing not working is no A/c condensor fan and it getting hot. compressor getting hot and tubes leading to the expansion valve are hot.

Any ideas??? is the control unit the the thingy in the dash ??

thanks so much this is a fun car

mojorizing

Wierd. I almost suspect a wiring issue, but check this out. With R14 pulled, jump out 30 and 87C - you should hear the condenser fan running on slow operating thru your new ballast resistor. AC should be cold with no cycling. Then jump out 30 and 87 for fast speed operation. AC should be cold, might be cycling.

If you're this far put R14 back to confirm that you still have a problem.