how cold is the a/c supposed to be - Page 3 - Diesel Forum

Dubco1 · 08-06-2005, 03:24 PM

Thanks

FOMOGO

96Cobra · 08-07-2005, 09:01 AM

Which dash vent are you guys measuring the temps in? I have read that the far right (passenger vent) will be the coldest, which makes sense, since it is closest to the AC unit. With OAT in the low 90's, I can get 41 degrees at the "middle" drivers side vent. I haven't tried the passenger side vent yet. I've done the bypass mod and insulated the "cold" lines under the hood.

Roger

mjl38351 · 08-07-2005, 03:31 PM

I would like to add something else as a consideration. I work on garbage trucks for a living and something we see very often with them is the evaporator core gets crusted over with crud. The evaporator is cold and (on Mack trucks the A/C thermostat which kicks compressor out has sensing probe inserted into evaporator) compressor cycles excessively. The air coming out the vents is not cold at all - sometimes not even cool. The airflow arcoss the evaporator fins is blocked by the crud which is usually a crusty layer of dirt and lint and such that has stuck to the moist surface of the evaporator on the side the air is blown into. I have saw over 20 degrees temp drop in air outlet temp by cleaning the crud off the evaporator.

The thing is this is not so hard to do on most trucks we have. I realize it would be much harder on most of the pickups we are relating to here. Has anybody ever saw their evaporator core to know if there is a layer of buildup that develops on these as well? It would seem to me to be very probable that the same situtation could be possible especially on high mileage trucks - mine has 208,000 now.

As EXCAV8TER has noted the debris that acculatates in the 3 cores will positively cause A/C related problems and also cause you to have engine overheating problems that happen going up long hills or prolonged hard pulls, then temps drop back down when pulling eases up. I have personally saw this many times especially on high mileage vehicles. Often times people start wanting to replace fan clutches and thermostats when the simple problem is there is a starving of airflow thru the cores to remove heat.

Mike

JustSomeDude · 08-09-2005, 12:28 AM

<font color="blue"> 18686 </font> <font color="red">1999-2006 MULTIPLE VEHICLES - A/C PANEL VENT TEMP DIFFERENTIAL
</font> SOME 1999-2006 VEHICLES MAY EXHIBIT A SIDE TO SIDE TEMP DIFFERENCE OF UP TO 10 DEGREES (UP TO 15 DEGREES FOR EXPL/MOUNT). THIS IS NORMAL. IF TEMPERATURE RANGES MORE THAN ABOVE STATED, PLEASE REFER TO THE WORKSHOP MANUAL FOR FURTHER DIAGNOSIS. TECHNICIANS SHOULD VERIFY INTAKE VENTS AND VACUUM LINES ARE CLEAR OF DEBRIS AND PINCHING. FOR DUAL ZONE, CHECK ACTUATOR POSITION PID (BINARY COUNTS). THEN PERFORM RELEARN PROCEDURE OF DOOR POSITIONS AND COMPARE TO ORIGINAL READINGS. IF LESS THAN ORIGINAL READINGS (COLD) OR GREATER THAN ORIGINAL READING (HOT), DOORS HAVE LEARNED NEW POSITIONS AND CONDITION SHOULD BE RE-EVALUATED. CHECK BLEND DOORS/ACTUATORS FOR A BINDING OR BROKEN CONDITION. IT IS CRITICAL THAT THE SYSTEM IS CHARGED WITH THE RECOMMENDED AMOUNT OF REFRIGERANT. DO NOT OVERCHARGE THE SYSTEM.
EFFECTIVE DATE: 06/21/2005

Mach1 · 08-09-2005, 05:19 AM

Caution, dont go out and add an extra pound of 134 freon. the 134 systems have to be weighted in, they are very sensitive to the freon level. Gauges usually will only get in the ball park.

Mine will get 38 on the drivers side vent..but I have top-secret AC mods..

BTW-anything below ~37 will start throwing ice balls out the vents..This is a sign that the system doesn't have the right amount of freon in it..