2000 Mack Ch613 AC issues

[DieselTech18]

i have a 2000 Mack ch613 with ac issues ac is working but not blowing very cold air the system is charged it did fail a vacuum leak test but could not find a leak anywhere after letting it sit and run how can i test the thermostat and or water valve what other issues could it be the compressor is working and the condenser has no visibly bad damage 

[Joey Mack]

So you pulled the plastic duct on the right side of the doghouse and peak inside at the core for dirt clogging the evap core ?  It is a common issue.  

[DieselTech18]

1 hour ago, Joey Mack said:

So you pulled the plastic duct on the right side of the doghouse and peak inside at the core for dirt clogging the evap core ?  It is a common issue.  

i pulled the instrument panel cover which house the heater core and evaporator and the thermostat switch i replaced the switch and it is still not working does the 2000 ch have an external ac compressor clutch or is it internal 

[Joey Mack]

External..  likely a Sanden pump. Have you looked at the binary switch on the receiver dryer? They can get loose at the plug and cause issues, similar to Freightliners of that era. Turn the A/C on and gently wiggle that plug.. see if the pump kicks on. 

[Mark T]

Never hurts to change the filter. That little switch in by the controller knobs likes to give up too.

[DieselTech18]

2 hours ago, Joey Mack said:

External..  likely a Sanden pump. Have you looked at the binary switch on the receiver dryer? They can get loose at the plug and cause issues, similar to Freightliners of that era. Turn the A/C on and gently wiggle that plug.. see if the pump kicks on. 

ac pump is kicking on ac is on just not blowing cold air it’s more luke warm i was told that the compressor and clutch can affect it 

[Mark T]

Check the filter.

[Geoff Weeks]

IF the compressor is running and you suspect a refrigerant side of the system to be at fault, you MUST provide pressures and temperature reading for anyone to do more than guess. Also how sure are you of the amount of refrigerant is correct in the system?

[DieselTech18]

4 hours ago, Joey Mack said:

External..  likely a Sanden pump. Have you looked at the binary switch on the receiver dryer? They can get loose at the plug and cause issues, similar to Freightliners of that era. Turn the A/C on and gently wiggle that plug.. see if the pump kicks on. 

it is a sanden pump it’s turning on but i’m wondering if it’s not broken internally and causing issues.

[DieselTech18]

Just now, Geoff Weeks said:

IF the compressor is running and you suspect a refrigerant side of the system to be at fault, you MUST provide pressures and temperature reading for anyone to do more than guess. Also how sure are you of the amount of refrigerant is correct in the system?

100% it’s a 3 pound system with a 9.1oz of oil 

[Geoff Weeks]

3 minutes ago, DieselTech18 said:

100% it’s a 3 pound system with a 9.1oz of oil 

How do you know you have 3 lbs in there, did you put it in by weight? how doyou know it STILL has 3 lbs in there when itwill not hold a vacuum?

[DieselTech18]

17 hours ago, Geoff Weeks said:

How do you know you have 3 lbs in there, did you put it in by weight? how doyou know it STILL has 3 lbs in there when itwill not hold a vacuum?

it was charged by a mac ac machine which has done the other 2 trucks i’ve worked on with ac issues just fine i talked to other people after explaining my issues said it could be the thermostatic switch next to the blower motor or the ac compressor the main question i want answered is about the ac compressor. i marked the pulley and the black plate with white paint marker and let it run after it was done running the two line did not match up correctly now i do know there is a very very small leak after it sit overnight it had lost roughly 00.200 pounds the air is luke cold after replacing the thermostatic switch running to the evaporator the dryer is working so is the evaporator the hot water valve is shut so if i could get a answer to my question it could narrow down everything and pointing it towards the ac compressor. thank you.

[DieselTech18]

21 hours ago, Joey Mack said:

External..  likely a Sanden pump. Have you looked at the binary switch on the receiver dryer? They can get loose at the plug and cause issues, similar to Freightliners of that era. Turn the A/C on and gently wiggle that plug.. see if the pump kicks on. 

binary switch?

[Joey Mack]

On the receiver dryer. The electric switch. It reads high and low pressure. It will affect compressor operation. But you said its pumping. What are the pressures when the A/C is on Maximum? Thats really needed for us to help you further. Also,,,, was too much PAG oil injected during the last repair? That can also affect refrigerant performance.  

[Geoff Weeks]

Again, without pressures and temperature, everything is a guess.  Pressure readings will tell if the compressor is compressing or not.

A/C work can get expensive if you "learn as you go".

[Geoff Weeks]

1 hour ago, DieselTech18 said:

it was charged by a mac ac machine which has done the other 2 trucks i’ve worked on with ac issues just fine i talked to other people after explaining my issues said it could be the thermostatic switch next to the blower motor or the ac compressor the main question i want answered is about the ac compressor. i marked the pulley and the black plate with white paint marker and let it run after it was done running the two line did not match up correctly now i do know there is a very very small leak after it sit overnight it had lost roughly 00.200 pounds the air is luke cold after replacing the thermostatic switch running to the evaporator the dryer is working so is the evaporator the hot water valve is shut so if i could get a answer to my question it could narrow down everything and pointing it towards the ac compressor. thank you.

Unless you painted that mark on with the engine and compressor engaged, I don't know how you expect them to be lined up? Belt will start turning before the compressor clutch will be energized, same when you shut the engine off, clutch will release before the engine stops turning.

[Joey Mack]

The paint mark is not going to help you. The pulley spins freely with the A/C off... The clutch is electromagnetic.. 

[Mark T]

Has anyone checked the blue filter in the cab ?  The one that looks like a big Scotchbrite ? They're a pain in the a$$ to get to and often overlooked. If it's dirty, no AC.

[Joey Mack]

Thats why i asked him if he pryed duct open at the HVAC unit. No answer..  

[Mark T]

🤷‍♂️ might be all that's wrong with it.   (lol)   my previous suggestion about it wasn't replied to either. Fairly common on those.

[Joey Mack]

Could be.  Most of my Mack truck repair has been on ones that work in the dirt.. of course i am not as smart as i need to be..  

[Mark T]

For what they do ?  you'd think they would've been easier to get at. Depending what you're working around, they may only last a short time.

[Joey Mack]

One outfit i worked for, i bought large blue woven plastic sheets and cut my own filters. They stopped large particles an didnt hold water that created a cake. I could pull it out, toss it on the floor, blow it out , and put it back..  all this under an hour... But... Why do I know ?? 😉

[Geoff Weeks]

13 minutes ago, Mark T said:

For what they do ?  you'd think they would've been easier to get at. Depending what you're working around, they may only last a short time.

IHC had them under the passenger seat, meaning the seat had to be pulled out of the truck to access😕