poor heater, anyone else?

I have a '90 xj w/ 4.0. It doesnt seem to heat very well in winter, the fan doesnt blow very hard. has anyone taken out their heater core, i'd like to pull it out and see if the fins are plugged, it seems like a big job.

It is a big job, you need to remove the whole dash, dealer has it listed as 8 hour s labor. Might want to try two other things first. Cheapest is to disconnect the two heater hoses and using a garden hose flush it out both holes, one at a time, flush backflush, flush backflush. Some have reported that some pretty nasty stuff comes out...
Second costs money, replace the plastic mixing valve with a new one and make sure it works....
Does it blow out the floor vents or is defaulting to the defroster vents, if it is defaulting to the defroster vents you probably have a vacum leak, check the hose that runs under the battery to the vacumn resevoir behind the passenger side bumper. Battery spluge rots the hose over time. Theres a bunch of other stuff that can cause it too...

Follow what this post says http://www.olypen.com/craigh/heater.htm

I used 4 ft sections of each size hose and collect the dirty water in a bucket. I used two 12 qt buckets and tuned off the water when both were filled. I kept washing forward and backward until I had clean water. If you don't collect in a bucket you will think it is clean when it is still dirty.

Coll, thanks for the info. will try to flush the heater core lines. i diod notice that when i move the temp sleector to cold, there is more airflow, which makes me think the core fins are plugged. had a older grand am once that had poor heat, took out the blower motor to get to the heater core w/ a toothbrush, cleaned what i could reach with that and it made a big difference. i dont think i can get to the core on the xj like that, not looking forward to pulling the whole dash.

Check your thermostat, I had a 92 that hardly had a heater on colder days. If you let it sit and idle it would heat a little but once you took off it would cool down. Pull out the thermostat to find it had fallen apart.

I have the exact same problem with my '90 and had the same thing with my '88 before I sold it. I have the same feeling that the fins are plugged or something. Also, I get much hotter air when I use the bi-lev setting in the AC section...doesn't make much sense to me but I'd be interested to find out what you learn