95 Lumina APV coolant fan problem

[wordman]

Hey everyone, I could really use some help on my daughters 95 Lumina 3.1 van. It had a blown head gasket and cracked radiator, I replaced rad. put new head gaskets on and had heads milled, put on a new water pump, thermostat, and both temp sensors and thought I was done. A week later and the coolant fan won't run right, so I replaced the fan relay and fan and still no luck. I can unplug the coolant temp sw. on the manifold and then the fan runs continueously and service engine light comes on. It only has one fan and the a/c didn't work when she bought it. I have 5 volts at the coolant sw. on the manifold so I am assuming the computer is doing is thing. Any help would be greatly appreciated.

[TexasGuy]

Did you bleed all the air out from the cooling system? There might be a bubble that doesn't allow a good heat transfer to a sensor. Remove a thermostat for this run and turn the heater on full. Keep the system open for a few mins while idling.