Having some issues with the condenser fans on my 98 Q45t. The fans do not come on at all. Turning on the AC, they do not come on. Connecting power directly to them and they work. Fan motors sound fine. Also, I have checked the relays per the FSM and they check out fine too. I have also tried another brand new relay. Weird thing is, when I jump the relays, the fans come on so that should indicate continuity through the circuit. Something is causing the circuit not to get continuity once the relays are connected, which is causing me to lose my mind

The fans do not kick in even when the temperature reaches above 95 Celsius. I am getting the reading from the OBD2 scanner via consult. The weird thing is, the temperature reading reads funny sometimes. When the car is idling, I rev it to about 3500 RPM and the temperature reading on the ODB2 scanner will actually drop a degree or 2 and then when I let off, the scanner reading will rise.

Initial reason as to why to troubleshoot fan issues is due to the A/C not getting cold when its fairly humid outside. When the temps are bellow 79 degrees and it gets somewhat cold. Recently had the A/C vacuumed and recharged. Honestly not 100% sure that the shop did fill it to proper pressure levels but assuming they did. The whole A/C system has been rebuilt as of recent and before the vacuum and recharge. Replaced evap core, dryer, condenser, and compressor. Did not replace the Triple Pressure Switch on top of the dryer but I assume it works properly due to the fact that once disconnected, the compressor turns off (not a clear indication, I know).

Any ideas?

You mention CONSULT. If you have one, did you run the fans in "Active Test"?
I'm not sure they are supposed to come on as soon as the AC is turned on.
The engine temp may need to be quite high, or the AC pressure get to a high level before they turn on. 95 Celsius is 203 Fahrenheit, and they should come on by 205 IIRC, and stay on down to like 195.
I don't have an ESM for them.
The relays get grounded by the ECM when conditions are met.

If your system is still not cold while you are driving down the road, with tons of air moving through the condenser, the fans are not the problem.
Good luck.

ezb57e wrote:You mention CONSULT. If you have one, did you run the fans in "Active Test"?
I'm not sure they are supposed to come on as soon as the AC is turned on.
The engine temp may need to be quite high, or the AC pressure get to a high level before they turn on. 95 Celsius is 203 Fahrenheit, and they should come on by 205 IIRC, and stay on down to like 195.
I don't have an ESM for them.
The relays get grounded by the ECM when conditions are met.

If your system is still not cold while you are driving down the road, with tons of air moving through the condenser, the fans are not the problem.
Good luck.

Unfortunately my OBD2 scanner does not have the "Active Test" option. From my understanding, the fans kick in either by: A) coolant temps get to a certain level B) A/C pressure reaches a certain level and C) vehicle speed controls them as well but I am a bit vague on how this actually works.

I tested the whole circuit from ECM to relay, then relay to Fans. Continuity exists throughout the whole circuit. FSM states that the ECM should get between 11-12v from the ECM pins (27/34) if the fans are not running. I am only getting about 4.6v from the pins.

Yesterday the ambient temp was around 64 degrees and the AC system cooled like it was around 65-70 degrees. Whenever its really humid and temps are high, the AC system is warm. My assumption is that the condenser is not getting cooled down properly and the temps of the Freon is getting to high.

Not sure why you are seeing 4.6 at the ECM. That should be voltage from the other side of the winding in the relay.
If you have 12V going in, and 4.6 on the other side of the winding, something is wrong there. Continuity is important, but there could still be unwanted resistance, maybe in a relay. If you ground 27/34, do the fans come on?

Still, your AC is not working when you are driving down the road. This is the real issue.
You really need to look at the system pressures or at least feel the hoses for temperature differences to understand what's going on.
There are some lousy rebuilt compressors out there, and also people sometimes damage brand new ones by letting a lot of liquid refrigerant into it right after the installation.
This damages the valves/or swash plate in the compressor and the system never develops sufficient pressures.
Try to get some readings.

ezb57e wrote:Not sure why you are seeing 4.6 at the ECM. That should be voltage from the other side of the winding in the relay.
If you have 12V going in, and 4.6 on the other side of the winding, something is wrong there. Continuity is important, but there could still be unwanted resistance, maybe in a relay. If you ground 27/34, do the fans come on?

Still, your AC is not working when you are driving down the road. This is the real issue.
You really need to look at the system pressures or at least feel the hoses for temperature differences to understand what's going on.
There are some lousy rebuilt compressors out there, and also people sometimes damage brand new ones by letting a lot of liquid refrigerant into it right after the installation.
This damages the valves/or swash plate in the compressor and the system never develops sufficient pressures.
Try to get some readings.

I am not sure either. Funny part is that my Intake timing solenoids are showing up on the OBD2 scanner now as well (both of them). Checked the circuit for continuity for both of the valves and the circuit is fine but getting 4.6 volts when turning the key to on position. Pulled one of the solenoids out, applied ground and power to it (per fsm)....plunger works. I am starting to wonder if I am having some other retarded ECU problem. Battery has 12.6-ish volts.

Went and bought some AC gauges from Oreillys. Bought the 100 dollar ones since I did not trust the look of the cheaper, plastic, 60 dollar ones. Turned the AC on, full blast and turned it to 65 degrees. High side stood slightly above 100 psi. Added a can of freon and the most it got to was around 150 PSI and then it stopped.

I hope you didn't overcharge it.
Depending on your ambient temperatures, 100 is sort of low for the high side.
What was the low side at?
Did it cool any better?

ezb57e wrote:I hope you didn't overcharge it.
Depending on your ambient temperatures, 100 is sort of low for the high side.
What was the low side at?
Did it cool any better?

I believe the low side was around 70ish psi. Can't remember exactly. Ambient temp showed around 76ish. It seemed like it cool a little bit better. Might just grab some cheap freon from dollar general and test it out in a day or 2.

Bought a s13 today to start a rebuild so I really don't feel like buying anything else at this moment. Plus, the whole thing is giving me a headache.

That's high for the low side.

ezb57e wrote:That's high for the low side.

Do you know what section in the FSM gives a clear indication as to what they should be? I can't seem to find the right section for it.

http://www.nicoclub.com/FSM/Frontier/1998/ha.pdf
This for the 98 Frontier manual, page HA-40.
Your pressures should be essentially the same.
The diagnostic charts after that are excellent and apply to most vehicles.