Howdy folks....here is the problem, best way I know how to describe.

So.....three days ago, I turn on the A/C, then the blower to high,,,works just fine...hot here so it took a minute or two to start cooling off..no problems.

later same day, get in Jeep to go somewhere and turn on A/C....I hear relay and compressor kick in...but NO Blower.

so I says Hmmmmmm......

after I return from where I was goin (see a little cutie to help my day along hee hee hee )

and I get out the schematics and looking into it, I see that there is a resistor pack in the circuit. I have replaced this item before several years ago as it was the culprit at the time. (now, when I was looking at this the day before yesterday i did not have a meter handy to check the resistor pack, I used one from work the next day. the result was the diode was reading 0 or shorted, both ways. ) So I figure ok its probably bad, cuz diodes should show infinite one way and 0 the other.
So I go to dealer (yes, I said dealer), and get new resistor pack for 10 bucks....not bad considering A-zone and oreilly didnt have em in stock and they wanted 33 bucks.
so I get back to where I am gonna swap this out, I put it in and nothing. no Blower. I still hear the relay but after a minute or so the A/C kicks off. so I check the big fusebox in the engine compartment and pull the relay (car is off). and it is really hot. Hmmmmmmm....so I put another relay in (always have spares), start the Jeep and same thing the A/C kicks on, no blower though. after a minute or so the compressor shuts off again....
Now, I have not checked the blower motor yet (doing this today) or the switch inside the control panel .
I will update after I do this.
Here is my question for you smart sons o' B$&^#^$ s out there.....

would not having enough pressure (adequate amount of refrigerant r134) in the system cause the fan not to operate? I cannot see how it would from the schematics, but I could be missing something.

Again, I will be testing the blower motor today and the switch too.

I know I don't have a leak in the system as the air was and has been really cold. A/C has been working great for a long time, couple years easy no problems.

Just wondering if you have seen this before as a result of refrigerant level or even if the maybe the compressor clutch switch is starting to go?
I dont think its that as it does kick on when i put lever to MAX or Norm or defrost or whatever. just no blower.

Thanks for any input and I will update as I progress!

cheers!

cpnwrench

 

You have a blower motor or wiring problem. The fan will run no matter what the compressor is doing. The reason the compressor is shutting down is because it knows that the system is not working properly (not exchanging any heat into the refrigerant) and it shuts down.

 

if theres no air blowing thru the evaporator the thermostat will shut down the compressor because its getting so cold with no air flo

 

Well, tested the fan motor, it is fine, however i have not pulled the switch (in the dash) yet and tested it.....

was looking closer at schematics and on the compressor...appears to be a diode/switch at the compressor....will keep looking and post.

thanks everyone for the input!!!!!!

cpnwrench

 

Well folks........here it is........I am stymied......

put in new thumbwheel switch.....only has four settings.

off
lo
med
hi

after putting new switch in (dash torn all to h%^&).....

turned key to run, didnt start the car.....and put the lever to "norm" for cooling and the temp lever is at cool.
then I turned the thumbwheel to med and the blower came on YAYAYAY!!!

Short lived it seems.......

after a minute, I started the jeep and the fan (blower motor) shut off.

I did hear the compressor kick in, but still no blower.

So here is what I have.....

New RELAY
New Switch
New Resistor pack

anybody got any ideas?

oh yeah getting 12v at the plug to my blower motor.
and When I wire the motor up to battery it runs fine...

help?

cpnwrench

 

just to clarify, are you getting 12 volts to the plug that feeds the blower motor when the blower stops working?

 

Also........after thinking about it.......

When I read the 12vdc from the blower motor connector, I wonder if I am getting enough current(amps load) to make the blower operate?
As this goes through the resistor pack before getting to the blower motor I am beginning to wonder if the NEW resistor pack is not allowing enough current to excite the blower motor stator etc etc etc....

When I hook the blower motor direct to battery, she runs just fine, but then again we are talking mucho amps here directly goin to blower motor..this is why I am thinkin the NEW reisistor pack might be limiting too much current..

I wish to thank freegdr and andyg for givin me something to think of......

Been studying the schematics....only other thing I can think of is the console heater/AC switch as it has to be in an ON position...MAX cool, or Norm or Bi-Level or Vent or Heat or Def...before the blower motor will come on regardless of the lo med hi position......will look closer at that this eve, yeah, I know tear the dash apart again!!!

Anyway,,if you guys have had this issue or know something (like hidden relay not in schematics, etc.) please let me know.

Thanks again!!!

cpnwrench

 

Yeah Cherokee40, I do get 12vdc at the plug where the blower motor connects...

now, I only get 12vdc when the climate switch is on ( MAX or Norm etc etc) AND the thumbwheel switch is in the Lo, Med or Hi position.

when I turn either the thumbwheel switch to off, OR the climate switch to off... the 12vdc goes away (which I would expect.).

cpnwrench

 

are you getting a ground when the blower dials on at the plug to the motor

 

Sorry to be redundant, but are you getting 12 volts at the motor, after it runs for a minute, and then stops? Just making sure....

 

"are you getting a ground when the blower dials on at the plug to the motor "

Ok, if I read correctly are you asking if I am reading the meter with the POSITIVE lead on the meter on the "green" wire (which is the "hot" side) and the NEGATIVE lead of the meter to Gnd or the block or frame.?

or.....

do you mean if I have the leads such that the POSITIVE lead is on the "green" (hot) wire, and the NEGATIVE lead is on the "black" or ground wire of the plug?

I only get 12vdc reading on the meter at the plug when I have the POSITIVE lead of the meter on the "green" (hot) pin of the plug and the NEGATIVE lead of the meter is on the "black" or ground pin of the plug.

(again, engine is on, thumb dial is on, and climate switch is on when reading is taking place.).

cpnwrench

 

FYI......

the blower motor only came on once.

and that was after I replaced the thumbwheel switch....and had the ignition on "run"

after I started the jeep, the blower quit.....

has not come back on since. and I tested the blower direct to batt and it is fine.

switch is fine, resistor pack is fine, am just wondering if the load on resistor pack replacement is limiting current to engage blower?

rrrrrrrrrrr

anyway, I do appreciate everyones input!!!

cpnwrench

 

tester pos to bat pos tester neg to plug neg 12volts present?????? tester neg to bat negative tester pos to plug pos 12 volts present ??????? with key on switch on if both produce 12 volts blower motor issue

 

Hmmmmmm....freegdr I see where you are goin....


but here is the kicker....when I wire up blower motor to batt direct

i.e., take plug off and use jumper wire direct from blower to the battery,

(both hot side and the rtn side to batt terminals)

the blower motor comes on and stays on until i remove the jumpers from the battery terminal.

however, I will test it today using that method you described.

could be the load thing I was thinking of and blower stator/brushes etc could be problem....

we will see.

thanks!

cpnwrench

 

if both these test come out good either motor or plugs issues