The condenser fan will not come on with A/C on. Fan motor works fine, tested with jumper wires. Purchased new fan control relay (behind grill), installed with no change - still does not come on. Compressor running, clutch engaged. Cools only when going down the road - air flow stops, so does A/C. Restricting time with A/C on to try and prevent emergency venting of 134 while testing. Stumped here. Any suggestions?