cooling fans

heres the problem,both cooling fans come on if climate control is on no matter what engine temp is,even when first started, and stay on, but don't stay on after ign is off even with high temp. if climate control is off they don't work at all. checked all relays and fuses even though i don't believe they would come on at all if any were bad.(not sure) there is a eng coolant temp sensor that shows to be hidden(page 8A-201-17 fig 32 in service manual)have not checked. two ac high side temp sensors that come up on scan P1535 high volts. ac doesn't seem to blow cold enough. could low freon pressure cause this, and where is the low side port to charge located at. off that subject i also get a 0717 no/low input tubine speed sensor si. huh? any help

I'm wondering if the A/C temp sensor is telling the computer that there is high pressure in the system, causing the fans to come on. Does it come on in defrost mode or every mode? Does your scanner give you a data stream? I'll check out your code numbers at work tomorrow and see if I can figure it out for you.

I remember someone saying the input turbine speed sensor(in the trans) is expensive to R&R. Unplugging the coolant sensor will make the fans come on at 160deg. and stay on, trying to protect itself as if the level is low."Low coolant" will also appear on the DIC.

thanks for the come back good buddy, oops wrong format.anyway it seems the fans come on only with engine running and in all modes as long as a/c light is lit. a/c comes on, fans come on, a/c cuts off, fans stay on (both on high,no matter the temp). when the a/c kicks in theres a big voltage drop, thus the high volt reading? i wonder could low pressure could cause this.and why doesn't the eng temp sensor kick in and turn on the fans with high temp reading, do the a/c sensors overide. the low coolant only comes on when there is low coolant,which happens when it all boils out if i don't run climate control. i didn't see what else was on the screen, my mech friend plugged it in. he's guessing bad a/c sensors, but not sure. i'm not sure but i think he showed me the turbine speed sensor on another motor & trans that was out of the car, and it was on the outside of case but hard to get to when installed. it reads 0717 no/low input turbine speed sensr si. and the other P1535 a/c high side temp sensr high volts.i think this is off snap-on 2500.i'm trying not to go on but giving as much info as possible to help you help me.thanks for the help guys. i figured if indy couldn't answer,he would challenge someone who might,thanks indy.anything appreciated.

Did your friend only pull codes ? Would he be willing to go to the engine data screen and see if a/c pressure reading high ? I'll try to find some info on the codes you have and see whats up .

i'm sure he will if he can.he doesn't have all the modules. i'm trying to get as much info as possible before i go back and bother him as little as i can, which i'm sure you understand. thanks again for your on going input.

Do you fans work normally without the climate control on ? I think you should start there. Let it run with the climate control set to off. Check for fan operation off the coolant temp sensor. For the code 1535- A/C High Side Temperature Sensor Circuit I found a few steps to follow.But the more I think about it It might be the sensor. It is located on the high pressure a/c line (look on the passenger side under the rad support in the front kinda like you want to change the low beam light you'll see it. It has a blue wire and a black/white wire. The sensor should be near ambient temp with key on engine off while the engine is cold See if you buddy can check that out with his scanner.

i'm not kidding you, i thought i was nuts. i can't believe with as much as i typed (i can't type) i hadn't said they didn't work at all w/cc off, but, i did in 1st post. thank god i'm not losing my (alleged) mind.this is harder than fixing it. if you don't mind please read them again and see if something jumps out at you.there are two sensors on that line, the other is in front center firewall. oldsmobile shows same part # on both but i grabbed them when at junk yard just in case and they have different p/n's.thats what i don't understand, i thought the temp snsr would override a/c snsr. not much help from service manuel.

I got info for a 98 (took a guess) In your first post you said the coolant temp sensor was hidden It says here it is behind the left rear of engine.When you snagged those sensors at the junkyard where there schrader valves behind them ? If they did I'd fire them on there .If you want I can send you the info I got In JPEG format.

You say the fan wont come on with temp. I'm looking at this schematic. On PCM pin #5 you have a dark blue/white wire (turbine speed in lo) on pin #6 red/black (turbine speed in high) and right next to it pin #7 black wire this appears to be sensor return for the coolant temp sensor and the EGR valve and TPS. Im starting to wander if you have a connection problem there because you have that 0717 transmission code.

I'm under the hood of mine and I don't think them sensors will come out without draining the A/C. Try plugging one of the ones you have in see what happens.

You say the fan wont come on with temp. I'm looking at this schematic. On PCM pin #5 you have a dark blue/white wire (turbine speed in lo) on pin #6 red/black (turbine speed in high) and right next to it pin #7 black wire this appears to be sensor return for the coolant temp sensor and the EGR valve and TPS. Im starting to wander if you have a connection problem there because you have that 0717 transmission code.

Did you ever find out if the coolant situation was related to the turbine sensor problem?

I had the same problem and I just went in an put in a toggle switch. I simply turn it on and off when I need it. Just don't forget to leave it on.