Ricky Beals Posted December 4, 2021 Share Posted December 4, 2021 (edited) New member here and first post. I have. 2003 Mack Ch 613 day cab. On the dryer for the AC there is a pressure switch and below it on a line is a green colored plug that has a schrader valve behind it. Any ideal what this plug is. Hopefully the picture loads Edited December 4, 2021 by Ricky Beals Correction Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 I think it's the high pressure switch for the engine fan... the dryer switch is binary for the A/C .. are you having trouble with it? jojo 2 Quote Link to comment Share on other sites More sharing options...
Ricky Beals Posted December 4, 2021 Author Share Posted December 4, 2021 (edited) We changed out the dryer, compressor and expansion valve and figured we would change them out. Parts guy kept saying it only had one pressure switch so I set to try and figure it out. Joined this forum and figured someone knew. I sure appreciate your help jojo. Do most folks change them out or is it waste of money? They ain’t bad but figured it was best thing to do. Edited December 4, 2021 by Ricky Beals Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 (edited) I really havent ever replaced one unless the wires shook so much, that the insulation fell off.. of course, replacing it isn;t a bad idea. I'm still not clear, why you are changing parts.. what is the issue? Edited December 4, 2021 by Joey Mack Poor spelling Quote Link to comment Share on other sites More sharing options...
Ricky Beals Posted December 4, 2021 Author Share Posted December 4, 2021 (edited) I just bought the truck and the guy that had it before me replaced the compressor and dryer. Ac wasn’t cooling good and we discovered the expansion valve was bad. We flushed the system and while waiting on expansion valve and thought we would replace the pressure switches just to be safe. I now understand the switch on dryer is binar. I didn’t know if the fan switch ( green colored switch) was bad to go out. Sometimes it easier to replace them now than later I reckon. Edited December 4, 2021 by Ricky Beals 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 its all good.... that is what this site is here for... keep in touch... jojo Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 have you pulled the duct on the right side of the of the HVAC unit and cleaned out the dirt that is in there... just remove the screws and and pry it back about an inch and a half. I made a cardboard tube that fits on my shop vac, and flattened it out so it can squeeze in to clean the evap core.. it's gentle enough to avoid damage as long as you are gentle with it... jojo Quote Link to comment Share on other sites More sharing options...
Ricky Beals Posted December 4, 2021 Author Share Posted December 4, 2021 No sir I haven’t. I’m guessing that’s a problem for these. So basically that’s where the evaporator core is at? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 yes... remove the cup holder first, the the tray it sits in, then the 2 torx screws in the panel ,then the torx screws on each side edge of the panel, then it will drop down and out from the bottom. there is a plastic guide pin in the bottom center edge, to clear.. no biggie.. once it is off,, to the right will be the 3/4" opening where a blue filter may be.. thats were the action happens... I bet the core is packed with dirt... you can try to blow it out, but sh!t will fly everywhere... jojo Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 4, 2021 Share Posted December 4, 2021 Yup and they get extremely dirty. As for the high pressure switch it’s the one on the top of the dryer. Only ever seen one go bad. Wiggle it and the compressor would work and then you would have AC. Then later in the day there would be no AC. Wiggle it again to get it back in business. Finally just replaced it. Quote Link to comment Share on other sites More sharing options...
Ricky Beals Posted December 4, 2021 Author Share Posted December 4, 2021 Totally off topic but you guys will probably know. I noticed a small drop of coolant coming from that sight glass on radiator. I have the two piece where top is radiator and bottom is reservoir. This something that goes out regularly. Do people go back with original thimble type glass bulb? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 you can remove it and reseal it, or give Vulva $600.00 for a single aluminum tank kit... jojo 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted December 4, 2021 Share Posted December 4, 2021 +1 on the reseal 👍🏻 Quote Link to comment Share on other sites More sharing options...
Ricky Beals Posted December 4, 2021 Author Share Posted December 4, 2021 10 hours ago, Joey Mack said: you can remove it and reseal it, or give Vulva $600.00 for a single aluminum tank kit... jojo How do you reseal? Is there an Oring behind the glass thimble? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted December 4, 2021 Share Posted December 4, 2021 PTF Pipe dope.... Quote Link to comment Share on other sites More sharing options...
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