Should Defrost temps be higher?

juan214

Full Access Members
Joined
Sep 11, 2013
Posts
484
Reaction score
51
Location
Stoughton, MA.
Hey guys,
Hopefully someone can answer this question.

JUST FYI:
Just did coolant change 60/40 and 195 degree stat last week. Well past due and in hopes to figure out an ongoing heating/cooling issues. Truck never got hot in the winter and never really cools in the summer (unless refrigerant is added). According to my scanner looks like the stat is opening and closing correctly. It gets to temp at 195-197 then opens and temp drops.

Started the truck this morning 51 degrees out. Ran it for 20 minutes with the defrost on The morning condensation/moisture was still on the windshield after 20 minutes except for three softball size spots at the defroster outlets. Looks like it got to about 80 degrees and maxed out at a 100. No big deal the wipers work.

Figured I'd tackle this early. Warmed up the truck (obviously it gets to temp). I open the glovebox and lower the door enough to gain access to the plenum. I have an access point where I cut it so I can inspect the blend door whenever I needed. Figuring that the 22 year actuator finally crapped out I'd take a peek. Blend door is opening and closing with no issues and sealing. Did notice cool temps in there though. Turned the setting to VENT and it got up to 120+.

These heating and cooling issues have been going on for years now. I always have a thermometer in the vent 24/7/365. My passengers care more about the temps more than I do. I drive with the windows open if either worked right anyway.

After seeing it get up to 120 degrees I figured would run through the settings (still 51 degrees out)
MAX/AC - Cool temps in the box, actuator moves, clutch engages
VENT - 120 degrees at vent, actuator moves, clutch disengages
PNL/FLR - 120 degrees at vent, actuator moves, CLUTCH ENGAGES
FLOOR - 120 degrees at vent, actuator moves, clutch disengages
FLR/DEF - 120 degrees at vent, actuator moves, CLUTCH ENGAGES
FLR/DEF - 120 degrees at vent, actuator moves, CLUTCH ENGAGES

Pretty dumb but I'm thinking the settings had to be run through like a tranny, sounds weird to me.

Vent blower tested with a piece of paper and it moves. Defroster blower tested with a piece of paper and it moved away. So no blower issue.

QUESTIONS:
1) Is the A/C clutch supposed to engage in heat settings? ANSWERED (YES)
2) Could something be disconnected (I.E. vacuum line)?

Thanks for any input.
 
Last edited:

juan214

Full Access Members
Joined
Sep 11, 2013
Posts
484
Reaction score
51
Location
Stoughton, MA.
Well it was 61 degrees this morning. I left the vent setting on last night for this morning heat test. Usually I leave the defrost on on winter nights. Started it with the remote left it running to its limit about 20 minutes. The truck was actually hot today for a change.

Leaving the defrost on to test that setting in the morning.
 

juan214

Full Access Members
Joined
Sep 11, 2013
Posts
484
Reaction score
51
Location
Stoughton, MA.
Well it was 49 degrees this morning. I left the Defrost setting on last night for this morning heat test. Usually I leave the defrost on on winter nights. Started it with the remote left it running to its limit about 20 minutes. The truck got just short of a 100 degrees. After driving around for an hour vent temp got to about 102 - 105 and slowly increases.

New Question:
Facing the engine, on the left side of the throttle there is a black T fitting. From the front of the intake manifold left of the thermostat housing there a tall nipple. A small hose connects from that and goes to the front on the T fitting. The Center port connects from there to PCV vacuum lines. The rear port continue to the rear of the engine.

If this is a vacuum switch and has low or no vacuum is this the source of my heating problems?
 

juan214

Full Access Members
Joined
Sep 11, 2013
Posts
484
Reaction score
51
Location
Stoughton, MA.
Well it was 53 degrees this morning. I left the Defrost setting on last night for this mornings heat test. Started it with the remote left it running to its limit about 20 minutes. The truck got just short of a 100 degrees again. After driving around for an hour vent temp got to about 102 - 105 and slowly increases.

Previous Question: ANSWERED
Facing the engine, on the left side of the throttle there is a black T fitting. From the front of the intake manifold left of the thermostat housing there a tall nipple. A small hose connects from that and goes to the front on the T fitting. The Center port connects from there to PCV vacuum lines. The rear port continue to the rear of the engine.

Answer: EV-256 Motorcraft PCV Valve

I put a small hose clamp on the hose near the PCV valve to seal it, it made no difference that I notice. Checked the PCV valve it made noise (not stuck) and was clean (inside still silver, no oil / carbon deposits).

Not sure if this opens when vacuum is applied and allows coolant flow through while the vacuum pulls heat from it the PCV valve.
 

Attachments

  • EV-256 Motorcraft PCV Valve.jpg
    EV-256 Motorcraft PCV Valve.jpg
    13.6 KB · Views: 2
Last edited:

plumcolr

Full Access Members
Joined
Mar 11, 2015
Posts
133
Reaction score
48
Location
freehold nj
Juan, the A/C runs when in defrost mode with outside temps above about 40 deg. That's why it blows cooler air even when the temp setting is at max. Theory is the air will be dryer blowing across the windshield and will clear it faster. However this may cause more moisture to condense on the outside of the windshield, which the wipers can handle. Most cars/trucks the A/C works this way.
 

juan214

Full Access Members
Joined
Sep 11, 2013
Posts
484
Reaction score
51
Location
Stoughton, MA.
Juan, the A/C runs when in defrost mode with outside temps above about 40 deg. That's why it blows cooler air even when the temp setting is at max. Theory is the air will be dryer blowing across the windshield and will clear it faster. However this may cause more moisture to condense on the outside of the windshield, which the wipers can handle. Most cars/trucks the A/C works this way.
Thanks for the great answer. Thought the 10-15 degree difference was an issue. I ended up starting a Prestone so called Heavy Duty Flush & Clean yesterday.
Try the same test with the a/c compressor unplugged.
I tried that last year didn't do much.
 
Top