A/C confusion
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Senior User
Joined: Jan 2019
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From: Los Angeles, CA
A/C confusion
When I run my front a/c unit (dash) I'd say the cool air is a 6 out of 10, but when I run the front a/c and the rear a/c together, my cool air in the front is a 8 out of 10.... what can I do to get the front unit to function colder without having to run both units?
Postmaster
Joined: Sep 2016
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From: Texas
Install ball valves that shut off hot coolant from flowing through the heater cores. One between hard line on passenger side and heater core inlet and one under degas bottle before it goes back into the Y. This will eliminate ALL hot coolant from flowing through the cores and heating up your air. In winter just open them up and you will have full heat when you need it.
Junior User
Joined: Mar 2005
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I don't have a good answer for you, but I have found that to be the case with every dual A/C vehicle I've ever had experience with. Dad had Chevy conversion vans in the mid 90s that were that way and I had a '99 and an '06 E-150 that both worked that way as does my '00 Ex.
Fleet Owner
Joined: Apr 2008
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From: 0,0,1
When I run my front a/c unit (dash) I'd say the cool air is a 6 out of 10, but when I run the front a/c and the rear a/c together, my cool air in the front is a 8 out of 10.... what can I do to get the front unit to function colder without having to run both units?
Hotshot
Joined: Mar 2011
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My 2000 Ex puts out 38 degree air from the in-dash vents. (The thermometer may be off a couple of degrees, but that's irrelevant.) When I turn on the rear A/C, the temperature coming out the front vents doesn't change, but the entire Excursion is cooler.
The inside of an Excursion is a lot of cubic feet of air to cool with an A/C system that has most parts in common with one cooling the cab of a pickup.
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Senior User
Joined: Jan 2019
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From: Los Angeles, CA
I'll second this.
My 2000 Ex puts out 38 degree air from the in-dash vents. (The thermometer may be off a couple of degrees, but that's irrelevant.) When I turn on the rear A/C, the temperature coming out the front vents doesn't change, but the entire Excursion is cooler.
The inside of an Excursion is a lot of cubic feet of air to cool with an A/C system that has most parts in common with one cooling the cab of a pickup.
My 2000 Ex puts out 38 degree air from the in-dash vents. (The thermometer may be off a couple of degrees, but that's irrelevant.) When I turn on the rear A/C, the temperature coming out the front vents doesn't change, but the entire Excursion is cooler.
The inside of an Excursion is a lot of cubic feet of air to cool with an A/C system that has most parts in common with one cooling the cab of a pickup.
I guess this calls for some checking out. It just so happens I have a calibrated thermometer that I use for work. I'll check it out when I'm off this freaking train and home.
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Senior User
Joined: Jan 2019
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From: Los Angeles, CA
Install ball valves that shut off hot coolant from flowing through the heater cores. One between hard line on passenger side and heater core inlet and one under degas bottle before it goes back into the Y. This will eliminate ALL hot coolant from flowing through the cores and heating up your air. In winter just open them up and you will have full heat when you need it.
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Postmaster
Joined: Sep 2016
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From: Texas
Same here, they both stay on, too much air space for just the front and makes very little sense to me.
Fleet Mechanic
Joined: Jul 2010
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From: Los Angeles, Ca.
If you want to block the coolant flow more than the factory valve already does there is no need to block both the inlet and outlet, and doing could cause problems. Just block the inlet and coolant can no longer flow.
Most likely what you're feeling is because the rear AC is helping the front one so it seems like the front one is working better when the rear is on.
Most likely what you're feeling is because the rear AC is helping the front one so it seems like the front one is working better when the rear is on.
Postmaster
Joined: Sep 2016
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From: Texas
If you want to block the coolant flow more than the factory valve already does there is no need to block both the inlet and outlet, and doing could cause problems. Just block the inlet and coolant can no longer flow.
Most likely what you're feeling is because the rear AC is helping the front one so it seems like the front one is working better when the rear is on.
Most likely what you're feeling is because the rear AC is helping the front one so it seems like the front one is working better when the rear is on.
FTE Remembers
Joined: Apr 2011
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From: Northern California
exactly this
Fleet Mechanic
Joined: May 2017
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From: TN
Anyone got the high and low side pressures for a properly operating Ex?
Not meaning to hijack, but surely that would be a good starting test point assuming both front and rear evaps are clean and clear.
Not meaning to hijack, but surely that would be a good starting test point assuming both front and rear evaps are clean and clear.
Cargo Master
Joined: Nov 2017
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From: Rock Hill, SC
There are exact pressures based on the 134A Freon T/P charts, but it's not a good reference point because pressures are greatly affected by temperatures, IE: airflow over each coil, ambient air entering the evap coil, ambient air entering the condenser coil, and by possible internal flow issues IE: dirty strainer, malfunctioning TXV. If the super-heat and sub cooling engineering values are a known quantity for that system, than you can perform those tests. Otherwise you could recover the charge, evacuate the system to 300 microns or less, and re-charge by weight per the rating plate to know you have a correct charge.