Switching between ac/heat

[Jake9000]

I have a m9000. The ac and heat work as they should. However, it doesn’t like to switch back and forth between the two. Where do I start to diagnose this?

 

[chim]

A good place to start would be a more detailed description. What does "it doesn’t like to switch back and forth between the two " mean? Button sticking? Runs hot for a while before cooling. Runs cold for a while before heating?

 

[Jake9000]

A good place to start would be a more detailed description. What does "it doesn’t like to switch back and forth between the two " mean? Button sticking? Runs hot for a while before cooling. Runs cold for a while before heating?

It is currently in ac mode. If I try turning it over to put out heat, it doesn’t switch over to heat it just continues to blow cold air.

The indicator light on the ac button goes off when I push it. When I turn the temperature to heat it will make a buzzing sound for a few seconds then the noise stops but it will still blow cold air.

 

[chim]

The A/C working is good news. A/C repair can get expensive fast.

I'm sure someone more knowledgeable than I will have some input. I was looking for a diagram that showed whether there may be a motorized valve in the system because the buzzing made me think a linkage may have come apart. Sure hope it's just something simple.

 

[dgtvrpepair]

Most likely the temp blend actuator is bad. It directs air flow to heater core for heat.

 

[Runs With Scissors]

I know it’s not an “apples to apples” comparison, but

I had a similar thing happen to my truck one time, and it was the blend-door attach point was broke/cracked/jacked up.

I would select a different mode and it would either “take forever” to switch over, or as it got worse, it would sometimes not do it at all.

Apparently the motor would just “spin” the attach point and occasionally it would/wouldn't “catch”.

Just an observation…..

 

[dvcochran]

It is currently in ac mode. If I try turning it over to put out heat, it doesn’t switch over to heat it just continues to blow cold air.

The indicator light on the ac button goes off when I push it. When I turn the temperature to heat it will make a buzzing sound for a few seconds then the noise stops but it will still blow cold air.

There is a pushbutton on the fan speed control that you push for A/C. Is this working (light going on/off)? Do you hear the compressor cycling when you press this button?
The temp adjustment is the old cable/slide style. If all the above checks out, the heater coil/A/C evaporator are overhead. As long as the long bolt inside the cab, overhead come out easily, it is super easy to remove the roof to access the box where the coil/evap reside. Look for the cable moving when some else moves the temp control slide handle. It could be as simple as the cable off at one end or the cable frozen up.
Separate the troubleshooting.
1. Assuming the tractor is Not having any overheating issues, radiator is full and clean, feel the heater hoses as far away from the radiator and see if they are hot.
2. Make certain someone has Not already put a manual shutoff in one or both of the lines. Open if added and test.
3. Remove the Temp control console inside the cab and make certain the cable is connected. See if it is moving freely.
4. Remove roof via long bolts inside cab headliner.
5. Check temp control cable at heater core end for operation.
6. If all this checks out, partially drain radiator (with system warmed up), remove engine side of heater hoses and drain. Carefully flow water through hoses checking for a heater core blockage.