Poor a/c performance at low speeds
 

I have seasonal allergies and I live where the pollen counts are extremely high from April to August. We start with tree pollen and then the grass seed pollen until they harvest all the hay. We are almost there they are removing the grass seed and bailing like crazy.
I told you that to tell you this. I run my a/c on recirculate all the time, I commute 30 miles each way 5 days a week. I live in the foothills of the Cascade mountain range and work out in the middle of the Willamette valley. Linn county Oregon is the grass seed capitol of the world or so they claim. I drive through grass fields all the way every day.
I noticed that the a/c does not cool well at low speeds but once I get up to highway speeds it freezes me out on maximum cool settings. That got me thinking that I have not heard the fans running in a long time. I let the car idle last night when I got home and the temperature kept climbing and no fans! Out came the fsm and I got the meter and started checking the fuses. Both 30 amp fan fuses checked good, I pulled the fan control module and checked the connections. All seemed good so I started checking the harness pin connections where they plug into the module and to both fans. I had pcm low on both the wires from the pcm so the fans should be on high. This model car has three speed fans and the pcm controls the speeds as needed for cooling and a/c performance. It provides ground to one circuit for low and ground to the other for medium and both for high. All the relays to make this work are in the fan control module. Low runs both fans in series to get the low speeds with half the volts just like the daytime running lights. Both fans also have a resistor to provide the medium speed and direct wires for the high speed. Both fans run at the same time on this car, one pushes and one pulls and they are offset for full coverage.
There are two grounds on the fan circuits one from the control module and one directly from the pusher fan. They are separate wires running to a single connector that overlays the main body ground bolted to a stud near the battery. Corrosion is not normally an issue here but the Ohm meter does not lie. I loosened the nut and tightened it and the fans came back! I will take the connection apart this weekend and polish the connectors and install some sealer to prevent this from occurring again.
Andy

Great info, Andy. I was going to suggest you check the cooling fans when I saw the title of your post, but see that you're sharp enough to have known what to look at. I know about it because it's a common problem on the Chrysler PT Cruisers and I'm a member of a forum on them. Most of those have a burned connector. Crappy design on placement.

Do the L cars at least have a cabin filter.

I am reminded of the lack of said technology every time I drive my s car on the highway........smells like 1979

Yes, there is a nice cabin air filter over the hvac intake. I might be able to get an expensive hepa type filter but recerc helps alot. The a/c worked perfectly all day yesterday.