A/c Season

[cgallamore]

a/c in berth working fine, next nite blowing hot.

a/c in cab working fine, don't know where to start looking for the problem?????????

[hatcity]

Are filters clean? Is there a filter? My cab didn't have a filter, was loaded up with "stuff".

[cgallamore]

i don't think it has a cab filter,

thursday nite it was ice cold, friday nite it was like the heater was on, instead of a/c

[hatcity]

On the pass. side in cab, you might have a large plastic duct type thing going into the A/C. several torx screws hold it in place. right where it connects is where my filter goes. removable, washable. Spray with febreeze and re-assemble. That is with the CX, don't know bout the CH, but probably similar. I'll try to get over to the truck in the morning and get some pics

Do you have an APU?

[cgallamore]

On the pass. side in cab, you might have a large plastic duct type thing going into the A/C. several torx screws hold it in place. right where it connects is where my filter goes. removable, washable. Spray with febreeze and re-assemble. That is with the CX, don't know bout the CH, but probably similar. I'll try to get over to the truck in the morning and get some pics

Do you have an APU?

nope on the apu, just sleeping with the curtains open for now.

[Gambi80]

I took the fresh air duct off and took off the covers for the hvac on the bottom of the dash last spring and took an air hose to the heater core/ac core...I was pretty suprised at the amount of shit on them, a layer probably 1/2 inch thick...bees wings(from corn) and dust. Afterwards I had 5 times the air flow and ice cold air. Those filters for the fresh air intake underneath the windshield on the outside are for decoration I think.

[Rob]

If I understand correctly you have adequate airflow or discharge from the vents in the sleeper berth. Most truck cab sleeper arrangments I've worked with use a separate expansion device for the sleeper from the cab. I've even seen an orifice tube used for the cab, and a mechanical TXV used for the sleeper. Locate the TXV, (thermostatic expansion valve) just ahead of the evaporator in the sleeper and the inlet side should be warm to hot, with the outlet side being much colder. If the temperature is about equal this can be a factor of either a malfunctioning TXV, (sticking), or a low refrigerant charge. Given the system will be an R-134A system it is probably low on charge. The integrity of automotive systems and the head/temperature pressures these systems operate at needs improvement.

When you charge a system with multiple TXV's in the complete system, ensure everything is operating meaning the sleeper and cab a/c in enabled, and blowers are operating through clean filters. Save yourself future headaches by dumping a 1 oz shot of flourescent dye into the system for anything that has a capacity over four pounds of total refrigerant capacity. This will make finding leaks very easy should they happen. I like the ratio of 1/4 oz per pound as it circulates adequately.

A/C is not hard to work with but the control of it can be troublesome.

Rob

[RowdyRebel]

My 2-70 air works great...was contemplating "upgrading" to 3-70 air last year, but Mack wants too much for the sliding rear window. Since it is slightly more than one of my truck payments, it will have to wait until June 2012...my first truck-note-free month.

[cgallamore]

If I understand correctly you have adequate airflow or discharge from the vents in the sleeper berth. Most truck cab sleeper arrangments I've worked with use a separate expansion device for the sleeper from the cab. I've even seen an orifice tube used for the cab, and a mechanical TXV used for the sleeper. Locate the TXV, (thermostatic expansion valve) just ahead of the evaporator in the sleeper and the inlet side should be warm to hot, with the outlet side being much colder. If the temperature is about equal this can be a factor of either a malfunctioning TXV, (sticking), or a low refrigerant charge. Given the system will be an R-134A system it is probably low on charge. The integrity of automotive systems and the head/temperature pressures these systems operate at needs improvement.

When you charge a system with multiple TXV's in the complete system, ensure everything is operating meaning the sleeper and cab a/c in enabled, and blowers are operating through clean filters. Save yourself future headaches by dumping a 1 oz shot of flourescent dye into the system for anything that has a capacity over four pounds of total refrigerant capacity. This will make finding leaks very easy should they happen. I like the ratio of 1/4 oz per pound as it circulates adequately.

A/C is not hard to work with but the control of it can be troublesome.

Rob

i did not have a chance to work on the a/c this weekend, thought i would just sleep with the curtain open this week, monday afternoon laid down for a nap and it worked perfect ice cold, i got a feeling this problem will come back?????????

[cgallamore]

i think it mite be in the temp control, got any ideas how to check this next time it happens?????

[Rob]

i think it mite be in the temp control, got any ideas how to check this next time it happens?????

When the discharge air is hot, or warm, is the airflow through the vents the same, or reduced as when the discharge is cold? If the airflow is reduced it sounds like the evaporator under the sleeper is freezing, or icing over due to a txv not operating correctly, or system overcharge of refrigerant. If the airflow is the same, it could be again the txn operating incorrectly, or the blend air door not responding to the controls correctly. The blend air door with restrict airflow from going over the heater core and routing it across the evaporator. You may have a partial blockage to the door's travel. Automotive applications are terrible about this.

Get a load going to Chicago, or Peoria, and stop by the shop. I'm usually around during the evening hours but call first, 309-219-2070. I can get a look at it for you.

Rob

[Mackpro]

i think it mite be in the temp control, got any ideas how to check this next time it happens?????

There is a actuator motor on top of the unit that moves a "blend door" this allows air to be drawn past the heater core or the AC evaparator core. You should be able to see this motor move when turning the temp knob back and forth ( it moves kinda slow)

[Mackpro]

There is a actuator motor on top of the unit that moves a "blend door" this allows air to be drawn past the heater core or the AC evaparator core. You should be able to see this motor move when turning the temp knob back and forth ( it moves kinda slow)

You can see the actuator in this breakdown.

[cgallamore]

When the discharge air is hot, or warm, is the airflow through the vents the same, or reduced as when the discharge is cold? If the airflow is reduced it sounds like the evaporator under the sleeper is freezing, or icing over due to a txv not operating correctly, or system overcharge of refrigerant. If the airflow is the same, it could be again the txn operating incorrectly, or the blend air door not responding to the controls correctly. The blend air door with restrict airflow from going over the heater core and routing it across the evaporator. You may have a partial blockage to the door's travel. Automotive applications are terrible about this.

Get a load going to Chicago, or Peoria, and stop by the shop. I'm usually around during the evening hours but call first, 309-219-2070. I can get a look at it for you.

Rob

seems the air flow is the same.

thanks, i will try to save you some trouble by doing the checks mackpro suggested, if i can't fix it i will try to scrape togather enough money for tolls and head for the windy.

[Rob]

seems the air flow is the same.

thanks, i will try to save you some trouble by doing the checks mackpro suggested, if i can't fix it i will try to scrape togather enough money for tolls and head for the windy.

The Kremlin within the communist state of Illinois?

Just pop the motor off of the shaft of the blend door. Make sure the door moves freely and do watch the actuation of the servo, (motor).

Rob

[cgallamore]

last time i was around chicago, i was going from fort wane,in. to milwaukee,wi. empty and the tolls where over $40.00. i need to learn my way around that stuff.

[Rob]

last time i was around chicago, i was going from fort wane,in. to milwaukee,wi. empty and the tolls where over $40.00. i need to learn my way around that stuff.

Yeah, it's nuts. I always go the two lanes but I like to piss people off too.......

Rob

[Mackpro]

seems the air flow is the same.

thanks, i will try to save you some trouble by doing the checks mackpro suggested, if i can't fix it i will try to scrape togather enough money for tolls and head for the windy.

There is also a service bulletin on the expansion valve freezing up in the sleeper, the fix is to replace the cab expansion valve. SB637021

Date: 08/31/05

Model: CX, CH, CXN, CHN

(Also applies to Mack Trucks Australia)

Sleeper Air Conditioner Evaporator Freezing and Icing — CXN, CHN, CX and CH Models with Blend Air-Type HVAC System

If sleeper air conditioner evaporator freezing and icing up complaints are encountered on CXN, CHN, CX and CH model chassis equipped with the blend air-type HVAC system, a service replacement front (cab) expansion valve (part No. 4379-RD570151) is available through the MACK Parts System. Replacing the cab expansion valve (front unit) located on the cab bulkhead will correct the ice-up condition of the rear sleeper unit.

Expansion valve part No. 4379-RD570150 is not applicable for this repair. Be sure to use the service replacement part No. 4379-RD570151.

[Gambi80]

last time i was around chicago, i was going from fort wane,in. to milwaukee,wi. empty and the tolls where over $40.00. i need to learn my way around that stuff.

It can be done! There are some 'free' ways up thataway. But Chicagolands expressway system is pretty discombobulated I'd rather just avoid it altogether. It is fun in a big truck though, people get the flock out of your way.

[Mitchell Thomas Headen]

Hey guys. Thanks for posting this. I have a 99 CX613 VISION and my AC barely blows out and not cold. Cool. I have water leaking all over my carpet. Drain hose on firewall not draining much at all. Can I remove that ductwork on the right side of console to get to the evaporator filter and to clean out a blocked evaporator drain? It's a bitch to reach on the firewall. Help a brother out.