Huntzman

Hey guys, having an issue with my kid's 99 Jeep GC.

The A/C seems to be only partially working. At first I thought it might be a coolant issue, but I topped it off and it's no different. Bottom line is cold air is coming out of the vents, but I don't think that it is blowing nearly as 'hard' as it should be. On a scale of 1-10 (compared to my Suburban's air on high) I would put it at about a 4 at HIGH.

Anyone know of issues like this and any advice ?

Thanks !!

Cherryokee

Huntzman,

Set the selectors for heat and dash vents. Confirm that blower speed varies with fan speed control min to max. Despite output temperature, did fan speed change? Was max blower output weak or strong?

If speed did not vary with controller then the blower motor resistor has failed. If the blower output did vary as expected but airflow was weak then you may have something obstructing airflow in the vents - check for stuff that may have accumulated at the cowl air intake.

BLOWER MOTOR RESISTOR
DESCRIPTION
Models with the standard manual temperature
control system have a blower motor resistor. The
blower motor resistor is mounted to the bottom of the
heater-A/C housing, under the instrument panel and
just inboard of the blower motor. It can be accessed
for service without removing any other components.
OPERATION
The resistor has multiple resistor wires, each of
which will reduce the current flow to the blower
motor to change the blower motor speed by changing
the resistance in the blower motor ground path. The
blower motor switch directs the ground path through
the correct resistor wire to obtain the selected speed.
With the blower motor switch in the lowest speed
position, the ground path for the motor is applied
through all of the resistor wires. Each higher speed
selected with the blower motor switch applies the
blower motor ground path through fewer of the resistor
wires, increasing the blower motor speed. When
the blower motor switch is in the highest speed position,
the blower motor resistor is bypassed and the
blower motor receives a direct path to ground.
The blower motor resistor cannot be repaired and,
if faulty or damaged, it must be replaced.

Willys55

If you have the electronic climate control you can check for stored codes:
I pulled this info from another site a few years ago:


1. To enter the self-diagnostic mode, depress the a/c and recirculate buttons at the same time and hold. Rotate the left temperature control **** clockwise (CW) one detent.

2. If you continue to keep the a/c and recirculate buttons depressed, the A/C control module will perform a Segment Test of the Vacuum Fluorescent (VF) display. In the Segment Test you should see all of the display segments illuminate as long as both buttons are held. If a display segment fails to illuminate, the vacuum fluorescent display is faulty and the a/c heater control must be replaced.

3. After viewing the Segment Test, release the A/C and Recirculate buttons and the display will clear momentarily. If there are no fault codes, the “00” display value will remain in the VF window. Should there be any codes, each will be displayed for one second in ascending numerical sequence (note: no effort is made to display faults in the order they occurred). The left side set temperature display will be blanked and the right side set temperature display will indicate current and historical codes (8 historical max) presently active.

Once all codes have been displayed, the system will repeat the fault code numbers. This will continue until the left side set temperature control is moved at least one detent position in either direction, by pressing both the A/C and Recirculate buttons at the same time, or the ignition is turned off. Record all of the fault codes, then see the Current and Historical Fault Code charts below for the descriptions.

Huntzman

Okay, so I checked the blower speed like you said, Cherryokee, and you can hear that it does increase from low to high and vice / versa, but the air coming out remains the same, very weak. What I would consider it to be the 'low end'.

I pulled the Jeep into the garage and checked what you said Willys55.

Held the A/C and ReCirc buttons and turned the CK one detent. Got a '52' steady. Never switched to another code, so I assume that is the only one?

Then I removed the cowling to check for any obstructions in the air intake area. Didn't see anything substantive, but gave it a good cleaning out with the shop vac anyway. Then re-checked the blower, but it remained the same.

Any thoughts / suggestions / ideas ?

FYI, for those who need to remove the cowling. Those damn windshield armatures where a B***H to remove. Guess after almost two decades (I assume they were OEM) they were a bit 'stuck'. Nothing readily accessible worked, so had to borrow my neighbors wheel puller to remove them.

FOLLOW-UP: Removed the blower motor to check the fresh air intake door. It was in the open position and the blower seemed to be blowing fairly hard, so I have to assume the issue is somewhere between the motor and the vents.

dave1123

I seem to have the same problem and have been dreaming up ways to check for obstructions without taking everything apart. I was lying in bed trying to go to sleep and it hit me. Take the blower motor out, start the engine, put the heater on floor only, and blast the floor vents with the discharge end of my shop vac! Any furballs should come out thru the blower housing, I would think. Worth a shot? I'm thinking tree seeds and other nonsense stuck in the heater core or supply ducts. With mine I think pine needles. They get into everything.

Huntzman

Interesting idea and would love to know how it works out for you. I actually have the same environment concerning the pine needles and you are right, they get into everything. I actually expected to see the air intake vent to be covered in them, when I removed the cowling, but to my surprise it wasn't as bad as I expected, so I am at a loss. I know the issue has to reside between the blower motor and dash vents (as explained above), but the next logical step is removing the entire dash, something I dread doing.

ablaize

I recently purchased a 2002 Grand Cherokee Limited that has this same issue. Air blows cold, just weak, even on high. Fan speed varies as you turn the ****, but high measures to about 2 as compared to my 97 Astro van with 4 speed settings. I had already replaced the blower motor resistor (as the fan didn't work at all when purchased). That got the fan going...blows cold A/C, but weak output still. Will run the diagnostics routine to see if I get any response code(s).

However, if anyone has any gems of advice....I'm all ears.

ablaize

After more searching, I found another thread with a similar problem described. Several of those people reported that the fan motor wires were crossed. I figured, "What the hell...I can try that"....low and behold...my A/C cranks now. This looked to be an original part...so not sure at all where the wires might have crossed...but it's working like a dream now.

Huntzman

Do you have a link to that ? I'd really love to check that out 1st, before I resort to pulling the dash apart or taking it to the shop !!!

dave1123

Dayum!! I'll have to try that! I replaced my fan motor with a Chinese one and thought I got it right, but maybe I didn't. What I did was spool up the old one and notice the direction of rotation, then hotwired my new one and made it spin in the same direction, I thought. Squirrel-cage fans don't more very much air spinning in the wrong direction. They also lose efficiency if not mounted close enough to the air inlet duct or air will spill over the rotor edges.

Looking back thru my mind's dead files, I seem to remember a problem I had with my Chevy truck. My heater blower quit so I got a junkyard one. The fan cage was not as tall as the one on mine but I installed it anyway. I didn't work very well. I swapped the cage from my old one and it worked perfectly. Not being tall enough, air was sucked back into the center and it lost pressure. Now I'll have to measure the distance from the mounting flange to the intake surface and see if there is too much of a gap between them. I may have to reposition the cage on the motor shaft.

Cherryokee

Well whaddya' know. I think I jinxed m'self. My blower motor began to cut-out intermittently and at the damn hottest, most humid days this summer (i.e., the past two weeks). The noise from the passenger side was becoming more unbearable than the heat and humidity (wife), the blower wasn't making any air movement nor noise at-all. I was happy with windows down as long as we were moving. Fast forward to this morning when I started the Jeep and turned on the A/C ... nothing. Grabbed my back-scratcher and tapped-banged around at the blower motor zone under the glovey from the driver seat. Zoom...ahhh...fresh cold blown air. Time for a deeper dive. Here's what I found, a nice hot power lead to the controller with the connector getting all gooey and melty...right after I download from Google Photo...

Cherryokee

Now I'm down to the whole "is it the chicken or the egg?" scenario. From my perspective, the harness was tight causing mechanical stress to the contact. Add vibration, shock moisture and what-have-you and you get an age-worn (17 y/o) contact that loosened and got warm, warmer, then hot a while ago. The heat translated out the receptacle, melting and displacing the plastic that holds the receptacle/wire crimp - the whole gradual failure spiral. The heat also conducted down the power pin and onward, melting around the power pin in the connector cavity of the blower motor controller. See photo of cavity, there's a melt-hole in the shell around the pin which I hope I can back-fill and seal with a big wad of dielectric grease. Only time will tell if the controller's internal power pin solder joint and circuit board trace was compromised. I'm going-in so I can silence the whiny noises from the passenger seat, else I may have to ask you guys to recommend a good divorce lawyer - joking - wish me luck!

Cherryokee

Oh joy! At this point I don't care if I'm right or wrong about the "chicken or the egg". The blower motor controller has suffered PCBA damage. I would attempt circuit board repair, still might, but am afraid it may pose the risk of fire/safety hazard in the passenger compartment. I called the stealership and they have the parts on the shelf ($125 for superceded controller P/N and a required wire harness adapter/repair kit). I learned about this, sadly a very common problem, from www.wjjeeps.com - just search on "Blower Motor Controller". Time to go pay the piper!

Cherryokee

The new parts require adaptation both mechanically and electrically. Everything needed was provided in the kit but I opted to use Raychem solder sleeves (left overs from the 80's, can't get them anymore) to join the new spliced-in harness leads, rather than the bare "W" crimps provided. No worries, they're still good to use, as the kit provided shrink sleeves too.

Dave1123, was right and I'm sure glad I read his entry above. I tested the theory by dismounting the fan and sure enough, if you follow the instructions in the kit, when you connect everything the fan spins backwards and that sucks. I don't know or care what's mis-wired, it just shouldn't happen. I popped/swapped the connector pins at the fan end of the two-wire cable and now it blows like a supercharged leaf-blower. The SOB was blowing old chunks & bits of insulating foam out the vents!

Huntzman, I want to suggest to you, if you haven't done so already, that you swap the fan leads to see if it makes the blower more blowy.

Is it possible that the OE setup always ran backward and weak but I just didn't notice as long as it was cooling the cabin...NAH!

Huntzman

Can anyone tell me what the correct direction the blower fan is supposed to turn in (Clockwise or Counter-Clockwise), so I can check and see if this might be the problem on my end as well?