Issues with heater core and a/c vents

281pony

Active Member
Aug 31, 2003
2,681
2
46
Oly, WA
my ****storm continues. i got my car with no blower boxes, we put them in a few weeks ago. its been so warm here, i didnt worry about heater/defrosting anything.

first thing. i am only getting warm, room temp air out the vents. the heater core was new when we put the boxes back in. the car was warm 170-180*, new thermostat, no leaks, no antifreeze smell. the temp does adjust with the dial. it cools down good, but it doesnt get warm/hot. any idea's? the coolant tubes on the intake have a bunch of chalky rust crap in them i saw when we assembled the top end. could this be an issue?

heater hoses are new, new antifreeze.

second problem; i was only getting air through the defrost vents. i read and installed the line from the a/c port on the tree, to the firewall vacuum line. i chased at line through the firewall and back to the controls. its all connected, no cracks, no vac leaks. however, the FLOOR vent now works, the defrost works, but the VENT does not work.

i get no air at all out the dash vents. it blows strictly out the defrost when its on the vent selection. i've looked around behind the dash as much as i could, cant find anything out of place.

when i first tested the vents after putting in the firewall vacuum line, i got a weird metal grinding sound from the engine bay only when selecting the VENT. it did this 2 or 3 times, only when it was at max flow. then it stopped, and has not done it since.

this car is driving me nuts
 
i just ran the codes after driving it for 15 miles.

i got a few bad ones, mainly code 66. bad mass air meter, i had figured as much, it idled good when i unplugged it. went back to a crappy idle/surging with it plugged in.

being that my alternator and maf now, apparently both went bad in less then 1 month/200 miles since i've had the car. could something be causing nasty electrical issues for me and frying this stuff? i have no signs of anything, but im horrible with electrical stuff.

it charges good now with the new 3g alt. i haven't thrown on a fuse yet, but i just ordered one today, along with a 4g grounding wire. it runs good, but its got me wondering why i've had 2 failures in 1 weeks time basically.

as far as my vent issue, ive got one code somewhat linked, not sure if this means anything. code 67 O.

neutral drive switch circuit failure, circuit open, or a/c input high? i have no a/c on the car, this was with ignition on only, no fan controls were going.
 
i got some great advice from the man, JT.

before its suggested, i did go over the surging idle checklist for faulty MAF. unfortunately, i've got nothing to measure with right now. my money is pretty tapped, so my broken screen on the voltmeter doesnt help. however, the car idle improves 1000% when pulling the maf connection off as suggested.

i did clean the element with non-flammable brake cleaner. it has a miss at cruising speed/light throttle, ocassionally i smell gas. perhaps its dumping fuel in, it is getting awful mileage. i seem to be getting about 10 mpg as a rough estimate.

it was suggested that the dash vents not functioning and the lack of heat go hand in hand. is this possible? im going to thoroughly check into what could be causing an obstruction of the dash vent doors tomorrow.
 
Here's some help for the HVAC stuff...



Diagrams courtesy of Tmoss & Stang&2birds
Mustang_AC_heat_vacuum_controls.gif


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 86-95 5.0 Mustang wiring Mustang FAQ - Engine Information Everyone should bookmark this site.


Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 94-95 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif