I installed a new micro switch in the control panel as advised. The heat & a/c came on,all the button lights come on except the econ button light(no problem).I can barely hear the fans blowing &very little is coming out the vents. The a/c compressor has been very noisy for a year now & needs to be replaced soon .The unit is a Sanden S510 with the rear pressure switch .I have not found a replace yet.Most compressors are the A6 GM type. Thanks Ahead & stay safe.
Sorry, what is the question in the post? Are you asking if the low blower speed is a problem or are you looking to source a replacement compressor, your location would be a help as this is a world wide forum, I am in New Zealand and probably no help even though I think I have a compressor from a XJ40 in the garage.
The 709 and 510 were used in the XJ40s.
I think they can be swapped as the electrical and refrigerant hose connections are compatible.
The blowers are a constant problem with fuse boxes and blower units causing issues.
Many posts for these faults so a forum or internet search will help.
First check that both fans are working. Easy enough to do by alternately pulling the fan fuses and then turning on the fans through all the speeds. The fan fuses are located in the left and right footwell fuse panels. The fuses are 20 amp and are in the left column 3rd fuse down in both panels.
If only one of the fans fail to run first check that the fuse is good. If it is, then the fan assembly is at fault and must be removed to be repaired. It could be that the motor is seized up, the fan circuitry is bad, or the relay inside the fan box is the problem.
Remember both fans need to operate to get proper airflow. If one fails the good fan just blows air back across the bad fan instead of up into the evaporator.
The problem is that I have heat but very little air flow. either the fans are not working correctly or the vents may not be opening .I have to find out how the vents work.I will find another new or rebuilt compressor somewhere out there. Thanks
Sounds like the blowers aren’t running. If you put the controls to defrost, you should hear them spin up even if all your flaps are closed.
There’s a few steps to check out, you aren’t the first down this road (hands up anyone who hasn’t had blower issues 
) so lots of flowchart stuff in the archive, use blower rather than fan for searches.
One thing I remember though is that the blower power wire (brown w/blue tracer) is live all the time even with ign off if things are copacetic.
The checklist goes …
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Do either of the fans run ? If not it’s probably a control panel problem.
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Does only one fan run ? Checked by pulling fuses.
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If both fans run, do they run at all speeds ? If not it’s probably the circuity inside the fan housing.
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Do both fans run at all speeds with poor airflow ? The problem is probably either one or both of the two blend flaps are not in the correct position. Or it could be (less probably but it happened to me) the evaporator is partially blocked with decades of debris.
Remember we’re only talking about airflow not air temperature, that’s a whole different problem.