Air conditioning Expansion Valves

[alcoon61]

Does anybody have a way to look up the part number for the expansion valves on a 07 cxn613 vin 14310. I see some mack expansion valves on ebay pretty cheap and would like to change mine but dont want to pull them just to get the part number and kinda hard to get behind the motor and see.

Figure there is one under the sleeper too there was on my freightliner are they the same part number or two different?

Thanks,

[Rob]

Does anybody have a way to look up the part number for the expansion valves on a 07 cxn613 vin 14310. I see some mack expansion valves on ebay pretty cheap and would like to change mine but dont want to pull them just to get the part number and kinda hard to get behind the motor and see.

Figure there is one under the sleeper too there was on my freightliner are they the same part number or two different?

Thanks,

Doubtful they will be the same. If original to the truck a Mack dealer can give you the information. If A/M, the model number from the vendor will help you out. Are these internal, or external regulated type valves?

Rob

[alcoon61]

I am not sure of the difference between internal or external. I have only change 2 in my life on the truck I had before this one and picked them up at freightliner. I try not to use the local dealer no more than I have to I think because I am a one truck operation they really stick it to me on price. I will just take them off and have my brother in law (works at RYDER) get em for me. He gets a lot better rate than me and employee discount also. Wished Walmart owned everything at least they dont charge one customer one price and the next customer a different price.

Thanks

[Rob]

I am not sure of the difference between internal or external. I have only change 2 in my life on the truck I had before this one and picked them up at freightliner. I try not to use the local dealer no more than I have to I think because I am a one truck operation they really stick it to me on price. I will just take them off and have my brother in law (works at RYDER) get em for me. He gets a lot better rate than me and employee discount also. Wished Walmart owned everything at least they dont charge one customer one price and the next customer a different price.

Thanks

I understand your plight believe me. If you call any Mack dealer they will give you the part number. I can then cross that OEM number to something you can use in the a/m. Barry's parts dept. is pretty fair on pricing so you may check with him. 888-304-6225 and ask for parts.

Internal compensation type valves do not have an external tube from them. External actually sample evaporator core temperature to regulate the flow of refrigerant into the coil, (evaporator). The external type are much more desirable and accurate, but more expensive.

Rob

[alcoon61]

Thanks Rob, after a lot of reading and fooling with it today I have about narrowed it down to what I think is high pressure valves instead of the expansion valves. When first cranked the a/c compressor runs. After running a few it will kick out and not come back on but the fan is not coming on like it should. I dumped the air tanks forcing the fan to run and in a few the a/c compressor will kick back in. Now I am scratching my head trying to decipher off several websites if the pressure switch on the high pressure line or low pressure line is the one signal the fan to come on. Horton which makes the fans says high pressure side (switch) . Then a found a mack apad bulletin that said the low pressure side switch controls it which makes no sense to me because with a guage on the low pressure side the pressure is not changing when it kicks out. dirt dobbers seemed to find my dual guage set and I am trying to clean them up so I can see what the high pressure is doing but wanna make sure I dont get dirt in the system. Any idea's as to which one actually is controlling when the fan comes in and out. I have a pressure switch in the line near the low pressure filler valve, and another on top of the dryer which I am assuming is the high pressure side.

Thanks

[Rob]

Thanks Rob, after a lot of reading and fooling with it today I have about narrowed it down to what I think is high pressure valves instead of the expansion valves. When first cranked the a/c compressor runs. After running a few it will kick out and not come back on but the fan is not coming on like it should. I dumped the air tanks forcing the fan to run and in a few the a/c compressor will kick back in. Now I am scratching my head trying to decipher off several websites if the pressure switch on the high pressure line or low pressure line is the one signal the fan to come on. Horton which makes the fans says high pressure side (switch) . Then a found a mack apad bulletin that said the low pressure side switch controls it which makes no sense to me because with a guage on the low pressure side the pressure is not changing when it kicks out. dirt dobbers seemed to find my dual guage set and I am trying to clean them up so I can see what the high pressure is doing but wanna make sure I dont get dirt in the system. Any idea's as to which one actually is controlling when the fan comes in and out. I have a pressure switch in the line near the low pressure filler valve, and another on top of the dryer which I am assuming is the high pressure side.

Thanks

Typically both of these switches for the high pressure limit, and the low pressure limit are in series with each other. If one switch is not satisified, the circuit is not complete. Compressor "short cycling" is typically a low charge condition, although high head pressure will certainly cut the system off as a safety precaution. These switches are typically self resetting also which would explain why it keeps trying to run.

Usually any switch plumbed into a receiver/dryer is the high pressure limit although most systems mount them very near the compressor itself. Typically the low pressure switch is close to the evaporator discharge line through the firewall. To get the system to run continuously while you charge it, jumper this switch in the low pressure side. This will fool the system and allow it to continue to run including the fan. Look for about 37 psi on the low pressure side when charging while running the engine at 1500rpm. This is a very basic setting dependent on a lot of outside factors but it will be cold there.

Rob

[alcoon61]

Still fighting with this a/c. Have replaced both high and low pressure switches, compressor, dryer, expansion valve and finally found apad troubleshooting info on the net and found a big part of my problem in the filter chamber in front of the evaporator looking for the t-stat which mack calls a freeze switch at the parts counter. There was a walmart bag sucked up in there in front of the evaporator filter. Went ahead and changed the evaporator filter and t-stat. comes on blows cold everything doing what it is supposed to do. Guage pressures look good low side running 35- 45 in 95 degree heat and high side just over 300 and everything drops back when fan comes on at about 310. Problem I am having now is it runs a while and then starts blowing hot. I can hear the thermostat on the evaporator cut out killing the compressor. Sometimes in a few it comes back on sometimes it dont like its hanging. Today I could smack the side of the thing with my hand and the compressor would kick back in. It does the same thing with the old thermostat too? Any idea's what might be going on. If you ever fooled with one of these t-stats on the evaporator it is written something like in- out and a arrow with colder written above it. It is all sealed in shrink and I cant see any adjustments on it. Is there a trick to how far it should be inserted in the evaporator tube? $800 spent so far on a walmart bag sucked up in the evaporator what a idiot I am but still having freak problems with it I cant figure out. Any help would be appreciated. I can get it going good and it might run all day and it might not. Yesterday I went to sleep and 4 hours later woke in 120 degree heat, smacked it and herd the t-stat click and had to shut the truck off 2 hours later freezing. Seems to always want to go on the blink in town it will kick out and start blowing hot, get stretched out on the highway and get it kicked in and it will run for hours. This thing is crazy. Beginning to think a 5 gallon can of diesel in the sleeper and a match would be the best solution.

Anybody have any thoughts or advice I would appreciate it. Shops are out of the question and I am too hard headed to pay for their trial and error also.

Thanks

[theakerstwo]

Still fighting with this a/c. Have replaced both high and low pressure switches, compressor, dryer, expansion valve and finally found apad troubleshooting info on the net and found a big part of my problem in the filter chamber in front of the evaporator looking for the t-stat which mack calls a freeze switch at the parts counter. There was a walmart bag sucked up in there in front of the evaporator filter. Went ahead and changed the evaporator filter and t-stat. comes on blows cold everything doing what it is supposed to do. Guage pressures look good low side running 35- 45 in 95 degree heat and high side just over 300 and everything drops back when fan comes on at about 310. Problem I am having now is it runs a while and then starts blowing hot. I can hear the thermostat on the evaporator cut out killing the compressor. Sometimes in a few it comes back on sometimes it dont like its hanging. Today I could smack the side of the thing with my hand and the compressor would kick back in. It does the same thing with the old thermostat too? Any idea's what might be going on. If you ever fooled with one of these t-stats on the evaporator it is written something like in- out and a arrow with colder written above it. It is all sealed in shrink and I cant see any adjustments on it. Is there a trick to how far it should be inserted in the evaporator tube? $800 spent so far on a walmart bag sucked up in the evaporator what a idiot I am but still having freak problems with it I cant figure out. Any help would be appreciated. I can get it going good and it might run all day and it might not. Yesterday I went to sleep and 4 hours later woke in 120 degree heat, smacked it and herd the t-stat click and had to shut the truck off 2 hours later freezing. Seems to always want to go on the blink in town it will kick out and start blowing hot, get stretched out on the highway and get it kicked in and it will run for hours. This thing is crazy. Beginning to think a 5 gallon can of diesel in the sleeper and a match would be the best solution.

Anybody have any thoughts or advice I would appreciate it. Shops are out of the question and I am too hard headed to pay for their trial and error also.

Thanks

I just when thru a deal like that on mine.A older mack but i give up and got a T stat that has a control knob on it and then connected it to the clutch thru a relay thinking maybe the factory which is new T stat was being damaged by the clutch amp draw. Why did they do away with the controlable T stat i dont know. Now i can keep the blower on hi keeping the evaporator dry yet control the temp.Also the red dot condensor on the roof is a plus.