bubbamobilin Posted June 3, 2011 Share Posted June 3, 2011 I know it's hot outside but what's up with my A/C? The older my truck get the worse the A/C gets. I put a new compressor on late last summer along with expasion valve and dryer. It did OK until winter but not great. Charged it up a few weeks ago and still the same old thing, 55 degree air. That's alright when I'm by myself, but now that school is out my two boys like to ride along and with three people in the cab 55 degree air don't cut it! Is it time for a new evaporator? Any help will be appreciated. Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/ Share on other sites More sharing options...
Rob Posted June 3, 2011 Share Posted June 3, 2011 I know it's hot outside but what's up with my A/C? The older my truck get the worse the A/C gets. I put a new compressor on late last summer along with expasion valve and dryer. It did OK until winter but not great. Charged it up a few weeks ago and still the same old thing, 55 degree air. That's alright when I'm by myself, but now that school is out my two boys like to ride along and with three people in the cab 55 degree air don't cut it! Is it time for a new evaporator? Any help will be appreciated.53-55 degree discharge air from the duct closest to the evaporator core is right on target for a properly sized HVAC unit for a given space. This provides the correct amount of dehumidification to the ambient air, along with heat removal. Ensure your blend doors are actuating correctly within the ductwork. Also door seals tend to leak more as they age.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78899 Share on other sites More sharing options...
shortstack Posted June 3, 2011 Share Posted June 3, 2011 I had the same problem with my truck. The A/C worked but not the greatest. I had to do some work to the blend doors-they wouldn't change from floor to vent and defrost so while it was apart I cleaned the evaporator real good. I had tried to clean it in the dash and it is about impossible to do (in a CH). After that it will blow 40 degree air out and this will be the second summer, still works great as long as I can keep it from getting stopped up again. Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78947 Share on other sites More sharing options...
David Posted June 3, 2011 Share Posted June 3, 2011 Check to see that both of your heater hose valves are completely closed. I'm running 47 degrees at the vents on 90 degree days and I haven't checked the charge yet this season. Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78958 Share on other sites More sharing options...
RowdyRebel Posted June 4, 2011 Share Posted June 4, 2011 What's A/C? Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78959 Share on other sites More sharing options...
bubbamobilin Posted June 4, 2011 Author Share Posted June 4, 2011 53-55 degree discharge air from the duct closest to the evaporator core is right on target for a properly sized HVAC unit for a given space. This provides the correct amount of dehumidification to the ambient air, along with heat removal. Ensure your blend doors are actuating correctly within the ductwork. Also door seals tend to leak more as they age.RobThanks Rob. I did check the evaporator today and it was stopped up pretty good. Also the drain was stopped up as well as the drain on the sleeper. I went to a local HVAC supply store and purchased some cleaner. I cleaned both evaporators and uncloged the drains. I did not give it a test run today but I'm sure there will be and improvement. Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78967 Share on other sites More sharing options...
Rob Posted June 4, 2011 Share Posted June 4, 2011 Thanks Rob. I did check the evaporator today and it was stopped up pretty good. Also the drain was stopped up as well as the drain on the sleeper. I went to a local HVAC supply store and purchased some cleaner. I cleaned both evaporators and uncloged the drains. I did not give it a test run today but I'm sure there will be and improvement.Glad to be of help. Get you a bottle or spray can of evaporator algaecide/deodorizer and spray into the intake plenum while running the a/c. Do not use the "recirculate" mode at first. While the a/c is running spray this into the outside intake vents. Then select the "recirculate" mode and again spray into the intake which is usually under the dash. This will kill the algae that inevitably grows due to moisture and humidity/dirt that collects on both the core itself, and plastic ductwork. Smells better too.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78972 Share on other sites More sharing options...
randyp Posted June 4, 2011 Share Posted June 4, 2011 What's A/C? heh heh,,I gree with you Rowdy,,,AC??,, I thought vehicles were DC current! randyp Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78974 Share on other sites More sharing options...
other dog Posted June 4, 2011 Share Posted June 4, 2011 heh heh,,I gree with you Rowdy,,,AC??,, I thought vehicles were DC current! randypYou and Rowdy might be on to something. I drove those Transtars and F-models for years and never had AC and it didn't bother me. But I could stay in the hayfield all day too, once upon a time. Now I can't stand the heat, and being in air conditioned comfort probably makes it worse when I do have to be out in the heat.I told Jeff before "if the AC quits, tha' motor might as well be blowed up, cuz I cain't drive it". 1 Quote Producer of poorly photo-chopped pictures since 1999. Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78985 Share on other sites More sharing options...
vision386 Posted June 4, 2011 Share Posted June 4, 2011 You and Rowdy might be on to something. I drove those Transtars and F-models for years and never had AC and it didn't bother me. But I could stay in the hayfield all day too, once upon a time. Now I can't stand the heat, and being in air conditioned comfort probably makes it worse when I do have to be out in the heat.I told Jeff before "if the AC quits, tha' motor might as well be blowed up, cuz I cain't drive it".I'm with you Tom! i spent many a summer in both the B and R-models working for my grandad,never really seemed to bother me back then,sometimes,i would even stretch out across the seat while waiting to un-load a catch a nap,but now it its not 43 degrees,and dark i ain't havin' it!..............Mark Quote Mack Truck literate. Computer illiterate. Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78989 Share on other sites More sharing options...
RowdyRebel Posted June 4, 2011 Share Posted June 4, 2011 I'm with you Tom! i spent many a summer in both the B and R-models working for my grandad,never really seemed to bother me back then,sometimes,i would even stretch out across the seat while waiting to un-load a catch a nap,but now it its not 43 degrees,and dark i ain't havin' it!..............MarkI've tinted the rear window of the cab, as well as the top 6" of the windshield....all that I can LEGALLY tint here in Illinois.I roll down the door windows and open up the wing windows to encourage a breeze to blow through.I have an aluminized windshield sun blocker sort of deal (wal-mart had 'em cheap last year) that blocks most of the windshield.I have 2 fans...a 10" that plugs into my inverter, and a 6" that clips to the sun visor and oscillates.Yesterday, I sat for 7 hours waiting to load. 95 degrees outside, sun beating down, asphalt parking lot. Stayed nice & cool inside the truck with the truck shut off (not burning any fuel).Ya'll can have that conditioned air. I like the natural stuff, myself. Even saved 40 pounds when I removed the compressor, condenser, dryer, belt, bracket, and lines from under the hood (all stuff that would have had to have been removed & replaced anyway if I ever decide to FIX the AC...so the labor is 1/2 done). Couple plugs in the firewall where the lines had been attached to keep things clean and I'm good to go. I know Mack appreciated not having to work around the AC stuff the last time my truck was in their shop getting the new cam, unit pump, lifters, etc...so it saved me a bit on labor. When I have to run the PTO-driven blower to unload, I open the hood. I've had a lot of guys ask me if I'm broke down, and I tell 'em it lets the heat go up instead of back toward the cab...also lets me poke around under there to check things out & make sure nothing is leaking/broken/missing/loose/etc... Even if I had AC, I'd still open the hood when I unload...just keeps things cooler under there. Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-78994 Share on other sites More sharing options...
chalupa Posted June 21, 2011 Share Posted June 21, 2011 Tackle this on my 98 CH day cab. New hoses, evap, ex-valve, comp and drier. All from Mack So everything new except condenser. Air temp at center ducts only 60. Slap guages back on and shows freon temp at 28-30 and head is 145 to 150.E-block is sweating and so is suction line, drain is open and dripping.This is on recirc. Numbers get worse on fresh.Wassup??? Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-80029 Share on other sites More sharing options...
rhasler Posted June 21, 2011 Share Posted June 21, 2011 Tackle this on my 98 CH day cab. New hoses, evap, ex-valve, comp and drier. All from Mack So everything new except condenser. Air temp at center ducts only 60. Slap guages back on and shows freon temp at 28-30 and head is 145 to 150.E-block is sweating and so is suction line, drain is open and dripping.This is on recirc. Numbers get worse on fresh.Wassup???Check your heater control valve and make sure it is closed fully. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-80031 Share on other sites More sharing options...
Rob Posted June 21, 2011 Share Posted June 21, 2011 Check your heater control valve and make sure it is closed fully.and the blend door(s).Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-80045 Share on other sites More sharing options...
Bollweevil Posted June 21, 2011 Share Posted June 21, 2011 Tackle this on my 98 CH day cab. New hoses, evap, ex-valve, comp and drier. All from Mack So everything new except condenser. Air temp at center ducts only 60. Slap guages back on and shows freon temp at 28-30 and head is 145 to 150.E-block is sweating and so is suction line, drain is open and dripping.This is on recirc. Numbers get worse on fresh.Wassup??? Assuming that you are using 134A, I would expect to see suction pressure to be lower and head pressure a lot higher, if the system were fully charged. Quote Link to comment https://www.bigmacktrucks.com/topic/19281-whats-up-with-my-ac/#findComment-80067 Share on other sites More sharing options...
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