On a 04 IH with a ISM is their a contiuous supply of air going to the fan clutch or does it presserise a short burst of air to keep fan disengaged? Right now fan clutch will disengage for a short time at every start of the engine but then engages and stays locked on.
Usually the fan system is plumbed with a normally open air circuit for the fan solenoid. Meaning if there is any kind of electrical failure the fan always runs. Most likely you have a sensor, coolant temp, inlet air temp, a/c high pressure that is telling the ecm to turn on the fan. It ignores it for a brief period during start up that is why it is cycling at start up. Many times it is the a/c pressure sensor or cucuit is at fault as it is out in front near the condenser usually not well protected. I would visually inspect all the wiring and sensor carefully first. It usually is a ground circuit out from the ecm then returning. Any break in the wiring will cause the fan to stay on. If you suspect the a/c sensor you can jump it with a paper clip or piece of wire to see if it turns off the fan with the engine running. One other thing you may notice is the fan will be released with the key on engine off. But when the engine is running the fan is always on. This also indicates that something is telling the ecm to turn on the fan.
It will release for a short time if you turn key off and on. I dont know if this is related or not but the heater would not switch from heat to defrost for part of the day when fan messed up. I will look it over monday.
Thanks tdcrash63.It was the a/c pressure switch. I looked every were for it and thought it didnt have one. I called Diamond IH in STJ and the picture showed it was in the cab under the passenger seat but i didnt see it turned out it was under the floor hooked to the block that hooks to the evaperator.
The KW that replaced this truck has a problem related to the fan. When you turn on the ac while seting steal the fan dosent come on so the ac presser will get high and kick the compress off then presser drops so it kicks in and out. You can turn the fan on and it works good. Shoudnt the fan come on when ac is turned on? It seams to operate wright as far as keeping the engine cool.
I don't think the fan should run continuously when the a/c is on. the a/c compressor is supposed to cycle on and off. does the a/c cool the truck?
No it dosent cool unless the fan is turned on or the truck is moveing. It will run for about 30seconds before the presser gets to high after the truck stops moveing or the fan is shut off then it starts cycle on about 5 seconds then off 15 seconds. Every car and pickup that had a fan that wasnt engine driven that i have been around when the air was turned on the fan would allso be turned on. It cools great if there is air going throw the condenser.
there is a pressure switch that makes the fan turn on if setting still or not enough air flow. on my pete, the switch went bad, fan would run continuously if the ac was on. switch was located on hard line near ac compressor. isx
It has a high and low on a ? block cant think of the name on the pass side firewall and a high presser switch on the compress line. They seem to all work.
mine was the hi press. on the compressor line. to get the fan to turn off,I disconnected the switch and jumpered the wires in the end off the plug. but if the truck wasn't moving then the air wasn't cold ( because it couldn't turn on the fan. manually turning on fan would get cold air) 525