ToolmakerMatt

About 5 to 10 seconds after i start my 2009 uplander the cooling fan come on at high speed and stays on till I turn the van off

oldchevy

Check the temperature sensor. Disconnect the wire and see if the fan stops.

ToolmakerMatt

i pulled the temp sensor out while the fan was running and the fans didn't stop.
i then checked the codes and got p0118 for the sensor being out.
I have also realized that i have no ac and the clutch is not even coming on.
few weeks ago i looked and the clutch was coming on and now its not

ToolmakerMatt

I tested the ohms on the temp sensor with the engine off for over an hour but still hot to touch and i got 500 ohms and after a few more hours i got 1300 ohms with the temp outside close to 30.
I then checked the voltage going in to the sensor and got around 5 volts but then slowly went up to about 9 volts

oldchevy

Have you checked the relays for the fan and the A/C? Possibly a short in the circuits?

ToolmakerMatt

I tested the relays with a 9v battery and an ohmeter for fans 1,2 and 3 and the ac clutch. I also checked the hvac fuse and everything checked out good
I then checked the socket the ac clutch relay was plugged into. When i by passed the relay the clutch came on and was reading 4 amps. I then plugged in the clutch relay and the clutch came on for a few seconds then went off(AC was turned on) when i pulled it out again and back in it didnt come on at all.I then jumped it with my ampmeter again and the clutch would stay on. I checked the voltage going into the relay switch and it seemed to have 14 volts if the ac was on or not. Shouldnt their be no voltage if the ac is turned off?

ToolmakerMatt

Today i popped the cover of the ac clutch relay and pressed the switch manually with the engine running and the cluch turned on and was blowing cold air. It didn't stop till i let go of the switch. I swapped the relay with one from the horn and fuel pump. As i plugged each relay in the clutch would come on for a few seconds then stop but then would no longer come on until turned the van off then back on again. I checked continuity on the ground before i turned the van off with the ac still on and had no connection. After i resarted it BEFORE i plugged in the relay with the ac on in i had a good ground. But then no ground again after i plugged the relay in and the clutch came on for a few seconds. The relays still seem to work fine with the fuel pump and horn. Maybe a bad ground in the ac switch???
And the cooling fans are still running full speed all the time
I am hoping these problems are all related