usrjcro11

Thanks to all that replied. Put Teflon dope on them

Should the water pump bolts have thread sealant on them. If so what type or brand. First time doing replacement. thanks again in advance

Ok thanks . Will start tomorrow disassembleing.

I can find service bulletin for 2007 but not 1993.

I am going with everything new. Hoses, compressor, condenser, evaporator , and expansion valve. I will have it clean before starting

It is on a 1993 mack ch613

Sorry if I put it in wrong place

Hope I called it correct. I have removed 4 screws that hold it.

Removed sensor and put propane torch on it. Did not like how long it took for it to lock fan. Got a new 200 degree lockup sensor. That was the lowest degree available. Thanks all.

Thanks for the plug tip

Will check with Mack on drl relay on 91 vs 94. Drl is grounded directly to ground. Now the tilt Ray gets its ground from the trailer tail lamp relay. This relay goes directly to ground. are daytime running lights suppose to only come when you release the brakes?

To make sure we are talking about same thing. The celenoid for fan is the unit I took picture of. It does have air going to it. I do not understand how when you cut key off the fan will lock. Where is it getting power and ground with key off to activate it. I see on wiring diagram it show engine water temperature sending unit going to dash gauge. The gauge has wire 17e08 going to one side of sensor and other side going to ground. My schematic does not show celenoid to control fan lockup. It does show a kysor dynair fan clutch air solenoid with only one wire going to it which is bkl08 which goes to ground on sheet 2 but it also says see sheet 5 for Horton dynair fan on sheet 1. I do not have sheet 5. i also see what is called water temperature sensor with wire going to Bosch module ms3 which is different from engine water temperature sending unit. i do not want to sound contrary. I am just trying to understand how it suppose to work. Understanding the problem is 90 percent of solving problem.

Swapped lines with air on tanks. It Activated pop off on top of solenoid. Fan did not lock. Control valve switch has 12 volts on one side and no ground on other side. This wire with no ground traces to one side of sensor. Fan does not lock with air on tanks with key off or key on. i was thinking fan free wheels till sensor closes when hot then goes to ground sending ground to control valve on radiator to lock fan

Will test in morning

I can put shop air to tanks. You want me to swap air lines and cut key on and see if air comes out exhaust or fan locks up. I am confused sorry.

further investigating wire diagram this is what I believe I have traced. Fuse 16 gets electricity from accessory relay. Output on fuse 16 is is wire 16a20 which goes to drl. Drl output is wires 7d20 and 7e20 and 7g08. 7g08 goes to park brake drl switch. Cannot find this switch. Maybe option??? 7d20 and 7e20 goes to tilt ray relay. One of the wires on tilt Ray relay is wire 7b20 which goes to headlamp switch. This is wire with 7.44 volts which I think is causing headlamps to stay on. when I pull fuse 16 headlamps go off. When I pull drl headlamps go off. i am thinking tilt ray relay is not unlatching when key is off. What is the purpose of tilt ray relay? Other wires on tilt ray relay : be08 which goes to directional signal switch dimmer bb10 which goes to trailer tail Lp relay thanks in advance

Removed dash cover where light switch is and checked voltage on female plug behind switch. Voltage and wire number in picture . These readings were with key switch off. Headlights are on even with lights switch unplugged. Only way to lights off is to remove drl relay. This relay came out of my 1991 MACK ch613. Is there a difference between 1991 and 1994 drl relay.Everything is fine with 1991 when I put drl relay back in 1991. I guess that 7.44 voltage on wire 7b2.0 is what is causing problem?

This is picture of control valve for fan by radiator

The wiring diagram in fuse cover shows one wire going to sensor and one wire going to control valve on radiator frame. One wire on both these going to ground.Both of these connectors are two wire connectors. The two wires are 1 12 volts and 1 ground. I did not see any cut and spliced wires on wireimg harness. Only the additional wire going to toggle switch in cab. Mr.joey MACK are you suggesting wires maybe wrong or the airlines going to control valve. Are the lines going to air valve push in type? I will get picture of valve tomorrow. Can the knurled knob turn to change settings?

I traced wires from temp sensor to toggle switch. The other side of toggle switch goes to ground. So when you toggle switch up it sends ground to the sensor and the fan locks in and turns. The wire on sensor has 12 volts on it when toggle switch is off. Trying to figure out what I need to do to make fan come on automatically and not by toggle switch. Thanks.

Here is picture of auxiliary wire that goes to toggle switch in cab

I unplugged the electrical plug by radiator that has air hose going from it to fan. I had read on here when unplugged fan should run. It did not. After further investigating before dark water temperature sensor had white wire going to it traced back to a cab toggle switch previous owner had installed. Cut switch on and fan comes on. When I drove truck on the pyrometer gauge did not move. Only gauges moved was oil and water temp. No movement of transmission or rearends. I had posted this before and somebody said to sensors with lighter. Thinking aloud that maybe have ground issue. Just learning.

The injection pump has plug of wires going to it

just bot this truck and trying to learn. Printed owners manual off and reading. The override switch on this truck does not stay engage when pushed up. It rocks down when released is this normal? Read on this forum about checking ground on vmac and ecm behind kick panel on passenger side. Startied trying to take bolts out but they just turn but not come out. Does this mean they are stripped?i I tried finding the bmt post about the grounds behind panel again but could not Am I correct their are grounds behind panel. The pyrometer gauge is not registering so I wanted to start eliminating all grounds first.Thanks

Thanks all. Will do rearend and trans sensors Big thanks to all