defroster question

Does anyone know a way to disable the a/c from coming on while in mix mode (air goes to floor and to windshield)?

yo t,

The air conditioning system is turned on and off by the function selector switch. When the function selector **** is positioned in any A/C mode (MAX or NORM), and the engine is running, electrical current flows through the A/C cycling switch (19E561) to the A/C clutch field coil (2987), the A/C clutch (2884) engages and the air conditioning system operates (providing ambient air temperatures are above a prescribed temperature). When the function selector **** is set in the DEFROST or MIX positions and the same above conditions are met, the A/C system will also operate. This allows the operator to select the proper air temperature (when the temperature control is adjusted) for defogging the windshield and side glass when necessary, by taking advantage of the dehumidification benefits of the air conditioning system. When the function selector is placed in any other position, current is stopped to the air conditioning circuit and the A/C compressor (19703) ceases operation.

MIX

NOTE: The temperature door can be set to full cool, full warm or anywhere in between. The function control **** does not affect the temperature blend door; this is governed by the temperature control ****.

In the MIX position, the airflow follows the same path as described for FLOOR position, except the FLOOR/DEFROST door is in the mid-position with an equal amount of air flowing to the heater outlet floor duct and the windshield defroster nozzle.

You could wire a toggle switch in the A/C clutch field coil harness to keep the ac from coming on.

Hey tjg,

M5 above gave you all the tech on it....now may I ask why you would want the AC to be off in that mode?

Hello

thanks for reply m5 and ron, sorry been busy with the holiday madness

Reason - Just to save gas, I always forget its on while on my way to work in the morning and it puts a bit of a load on the motor when it doesn't really need to.

I find a little warm air to the windshield in the wintertime is all it needs to defog.

One recent morning I discovered I wasn't getting any heat even when the thermostat was turned all the way up, in fact my car was actually getting colder due to the fact the a/c was running while in mix mode. Turned out to be a clogged heater core, but it seemed to me at the time to be a waste to run the a/c compressor, especially in the winter when not really needed (We have dry winters here in Cali).

The option to add a toggle sounds perfect ...I'm just no good at electrical and haven't had much time to digest the diagram given.

If could provide a version for dummies, I would greatly appreciate

Happy Holidays All

yo T,

When looking at the AC Compressor under hood from front bumper, the A/C clutch field coil is on front of compressor;

there is a wiring harness with two wires connected to the clutch



with engine off

cut the Gray (GY)/with White (W) striped wire in half; strip both sides a bit so that a weatherpak type connector (most use an Insulated Crimp-On Butt Connector) can be used to join these two cut wires to a new 2 wire section; when buying wire and connector, tell sales people that the circuit is protected by a 15 amp fuse and is in your Bronco (12v DC nominal)



then run a similar sized new 2 wire section back to drivers side in side cab via the clutch blank that is below the Master cylinder. Here is a pic; ensure a previous owner or shop did not attach anything to cab side; use a 1/8" bit for a pilot hole, then a larger size for the new 2 wire section;



when buying the new 2 wire section, get a grommet that will fit snug against the clutch blank hole as well as the 2 wire section, place it on the 2 wire section before hooking the wires up to the switch or the cut wires.

drill bit should be suitable size to fit grommet snug into clutch blank

at A/C clutch field coil, strip wires and hook up one from new wire to Gray/W wire, either side

and other new wire to other side of the cut gray/white

Inside cab install toggle switch

http://demandware.edgesuite.net/sits_pod26/dw/image/v2/AASR_PRD/on/demandware.static/Sites-radioshack-Site/Sites-master-catalog/default/v1419159620877/images/55050549_00.jpg?sw=350&sh=350&sm=fit

Since fuse for the circuit is 15 amp, get a 20 amp rated switch for about $12.00 @ radio shack

hook up both new wires to it

one wire on one terminal and other wire on remaining terminal

I'll post this for now and edit later.

yo, Some videos

https://video.search.yahoo.com/yhs/search;_ylt=A0LEVvwJ4JZU7zAANEoPxQt.;_ylu=X3oDMTBsa3ZzMnBvBHNlYwNzYwRjb2xvA2JmMQR2dGlkAw--?p=basic+automotive+wiring+how+to&hspart=avg&hsimp=yhs-fh_lsonsw

How to wire up an "On-Off" toggle switch.

https://video.search.yahoo.com/video/play;_ylt=A2KLqIKo4ZZUOW8An4v7w8QF;_ylu=X3oDMTBycTlydWI1BHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDOA--?p=basic+automotive+toggle+switch&vid=6ea43696cbbee54171e1fde398291311&l=2%3A12&turl=http%3A%2F%2Fts1.mm.bing.net%2Fth%3Fid%3DVN.608038632169868808%26pid%3D15.1&rurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DMn9G1wBGaIQ&***=%26quot%3BOn-Off%26quot%3B+%28single+pole%29+Toggle+Switch+for+automtive+use+with+Wiring+Products&c=7&sigr=11bvtsvgm&sigt=12l8t9ha5&age=0&fr2=p%3As%2Cv%3Av%2Cm%3Asa&hsimp=yhs-fh_lsonsw&hspart=avg&tt=b