Alternator, Blower Fan, AC Clutch?

Magus2727

New member
I have been battling my AC not working for the longest time and we are having record highs out here hitting at and over 100 F. I think I may have narrowed the problem down to possibly an electrical problem.

When driving at freeway speeds (dont worry I was not the one taking the picture) My volt meter can drop as seen here and even lower to just at the white line:


But even when I turn everything off its in the middle between the low side and 14V. I know dash gauges can be less accurate, but a dash voltage gauge like this should be fairly accurate. I have measured the voltage at the battery with everything running MAX AC max blower and measured 13.7V on the battery. Turned it all off (the AC and Blower) and still measured 13.7V at the battery. I know you usually see more of a 14.5-14.7V with the vehicle running shouldn't I? It starts great every time regardless of how long and low the voltage needle on the gauge is. How good are the tests they do at auto zone that attempt to load down you alternator and test it while on the vehicle?

The voltage gauge also does not matter if I am accelerating, idling, braking, or maintaining a constant speed. (my freeway speed due to my tire size is just at 2,000 RPM)

Could my alternator have some damage to it or just be old enough (have 196k miles on the jeep and think its the OEM one still).

Or I was thinking since I am seeing alright voltage (above 12v) on the battery the voltage drop I am seeing has to do with something in the cluster panel? How much should the needle change when you turn the blower on (either with AC or just Vent)? The gauge would lead me to believe that it might be seeing as much as 1-2 volt drop from off to full. So could my Blower be going bad? It does make a sequel when its cold out for a few min until I am guessing the bearings warm up.

Also when you select max AC the blow should push out more air with out changing the blower speed? While diagnosing this today I observed that the air output actually drops when I switch from AC to MAX AC.

Last thought would be due to the combination above possible items does an AC clutch need a higher voltage to always properly engage? If I am observing a lower voltage (even though the battery has 13.7V on it) after the relays and fuses etc. for the AC clutch could my gap be slightly large enough that the voltage threshold is not lower so with my other possible voltage doping problems I might just be seeing a to large of a gap on the AC Clutch?

When I have the blower on the lowest setting and the AC on I usually dont run into any problems with the AC clutch not engaging, its only when I up the fan speed to try and cool down more. And With 100F outside even with the windows down after running to the store the AC on the min blower speed is not even noticeable.


Any help and or thoughts would be much appreciated!
 

Ecomike

NAXJA# 2091
NAXJA Member
You have several problems, that are unrelated. First, it sounds like the alternator has lost one side of the diodes, and yes, with no loads it should read at least about 14.3 Volts.

Check it fully loaded, head lights on brights, AC blower on Max, clutch engaged, brake lights on...and I bet the battery reading at the battery drops to 12.7 or lower.

Ignore the absolute values on the Jeep Voltage gauge in the dash, they are JUNK!!!!

You may have a clutch air gap issue. Hard to tell at this point.

You do have an HVAC vacuum line leak or a bad damper door vacuum valve (leaking diaphragm). Check the vacuum lines at the firewall near the AC expansion valve, and the rear of the dash HVAC controls, and the vacuum line at the valve under passenger side dash. If those are all good, look deeper under the hood, front passanger side bumper has a vacuum bottle, and hose running under the battery.

Blower may be giving some warning signs. Check the drain duck bill on the firewall for junk that might holding water back from draining from the AC evaporator box.
 

Magus2727

New member
Thanks! Will check these things out as I get time... do the load checkers at places like auto zone that loan your car down work at all to possibly identify if my alternator has problems also?
 

Ecomike

NAXJA# 2091
NAXJA Member
Thanks! Will check these things out as I get time... do the load checkers at places like auto zone that loan your car down work at all to possibly identify if my alternator has problems also?
Yes, but a volt meter at the battery will tell you if the alternator is the problem. AZ is better at load testing the battery, but you can check the battery by checking the battery voltage while cranking. If it falls under 10 V at the battery while cranking, the battery is either bad, or needs recharging, which can be done with a charger, then retest, to verify if the alternator was not charging or the battery was not taking the change.
 

souske

New member
Chapter BOD
You might try hosing the alternator out with some contact cleaner (not running)

Got mine to bring the voltage back up for a few months
 

pismo61

New member
I have been battling my AC not working for the longest time and we are having record highs out here hitting at and over 100 F. I think I may have narrowed the problem down to possibly an electrical problem.

When driving at freeway speeds (dont worry I was not the one taking the picture) My volt meter can drop as seen here and even lower to just at the white line:


But even when I turn everything off its in the middle between the low side and 14V. I know dash gauges can be less accurate, but a dash voltage gauge like this should be fairly accurate. I have measured the voltage at the battery with everything running MAX AC max blower and measured 13.7V on the battery. Turned it all off (the AC and Blower) and still measured 13.7V at the battery. I know you usually see more of a 14.5-14.7V with the vehicle running shouldn't I? It starts great every time regardless of how long and low the voltage needle on the gauge is. How good are the tests they do at auto zone that attempt to load down you alternator and test it while on the vehicle?

The voltage gauge also does not matter if I am accelerating, idling, braking, or maintaining a constant speed. (my freeway speed due to my tire size is just at 2,000 RPM)

Could my alternator have some damage to it or just be old enough (have 196k miles on the jeep and think its the OEM one still).

Or I was thinking since I am seeing alright voltage (above 12v) on the battery the voltage drop I am seeing has to do with something in the cluster panel? How much should the needle change when you turn the blower on (either with AC or just Vent)? The gauge would lead me to believe that it might be seeing as much as 1-2 volt drop from off to full. So could my Blower be going bad? It does make a sequel when its cold out for a few min until I am guessing the bearings warm up.

Also when you select max AC the blow should push out more air with out changing the blower speed? While diagnosing this today I observed that the air output actually drops when I switch from AC to MAX AC.

Last thought would be due to the combination above possible items does an AC clutch need a higher voltage to always properly engage? If I am observing a lower voltage (even though the battery has 13.7V on it) after the relays and fuses etc. for the AC clutch could my gap be slightly large enough that the voltage threshold is not lower so with my other possible voltage doping problems I might just be seeing a to large of a gap on the AC Clutch?

When I have the blower on the lowest setting and the AC on I usually dont run into any problems with the AC clutch not engaging, its only when I up the fan speed to try and cool down more. And With 100F outside even with the windows down after running to the store the AC on the min blower speed is not even noticeable.


Any help and or thoughts would be much appreciated!
With my scan guage my volts are between 13.4 and 13.8 with and with out load.My dash guage always drops like yours does also.All my parts seem to be original at 160000 miles.Never had a battery problem.When i spooled on my synthetic rope(no load) though ,I did it with out the engine on and it barely started.I believe my97(125000 miles) wrangler ran the same also.Never saw 14 volts on the scan guage.Also I think the battery temp sensor may have something to do with the charging.I think when its hot it charges different then when cold,not sure though.Some here will know for sure.
 
Last edited:

old_man

NAXJA Member
NAXJA Member
Stupid question.....are you sure the system is charged? Remove the low pressure limit switch connector and short across it. If it then runs, you have a leak somewhere.
 
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