QuestionThanks for your help.
I just completed a 300 mile trip using the car's air conditioning. The outside air temp was about 30 C with 60% relative humidity. Here's what happened on the trip:
8:30 am - started the car and ran the A/C; outside was 26 C, 60% humidity; very cold mist came out of all 4 dash vents for about 15 minutes, and the air was VERY cold.
From 9:00 am to 2:00 pm, the A/C was operating on the following cycle, fan blower on 3/4, temp set to max cool:
Switch ON:
1. first 10 minutes - all four vents provided cold air (1 driver side, 2 centre dash, 1 passenger side)
2. next 5 minutes - all vents provided cool air, but only centre right vent provided cold air
3. next 5 minutes - all four vents provided warm air; no apparent cooling
Switch OFF; fan left on
4. next 2 minutes - system switch turned "OFF" and fan blower kept on; all vents blowing warm air
5. next minute - driver's side vent blowing slightly cool air; other vents blowing warm; switch is OFF
6. next 2 minutes - all four vents blowing warm air
7 A/C switch turned on and cycle repeated.
During each cycle, there was no misting of the windshield, no smell of coolant, no wet spots on carpet. The mechanic doubts it's the heater core.
Hope this helps. My mechanic (with A/C training) is stumped.
thanks
Paul
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Followup To
Question -
Dear autohelp,
This is 95 Camry LE 2.3l 4-cylinder, 270,000 kms.
The a/c blows cold (35F)for about 10 minutes, then only cool for another 10 (50F)before blowing warm thereafter. If I turn off the A/C for 5 minutes, I can repeat the cycle.
My mechanic has replaced the expansion valve and evaporator to solve any earlier leak (R134A). A/C line temps up- and downstream of the compressor are roughly equal. Recently, we've been trying to vary the pressure settings, thinking there is an icing problem. so far, no luck.
In reading your forum, I think it may be a heater core problem. I always have a blue/grey film on the inside of my windshield, especially in summer, and especially when I use the a/c through the window defroster. The ducts smell musty, but no moisture on the carpeting (yet...).
Could the heater core be causing this unusual cycling of the a/c?
Thanks
Paul
Answer -
This is a very good possibility. You need to have the coolant system pressurized for at least an hour to see if any engine coolant leaks out of the evaporator drain hole under the vehicle.
AnswerThere is an easy way to find out if it is the heater core. Disconnect both heater hoses from the heater core and put a fitting to connect the heater hoses together thus by-passing the heater core and after some time see if your A/C starts to work correctly.
When the evap was replaced are you POSITIVE that you adjusted the damper door control arm from the programmer to the damper door correctly ?.
