Hmmm, on both my 2001 Accord and my 2006 TL, I can engage the windshield defroster and still disable the A/C compressor.

 

There really is very low pressure in any part of my cooling system, And it could be that I have a little bit of pressure in my expansion tank because i have it topped up to overflowing in an attempt to clear any airlocks. And yes I have all the return pipes and other pipes as you would expect. I would be happy to send a pic if you like. So the interior heat, I can turn off the AC which is first thing I would do. We have no need in this country.
So pressing off/auto together does still bring up 88 88. But apparently my car is unique lol.
I have decent heat in the left side but cold on the right. Ive tried every combination of airflow to window, floor, vents. Even full heat to right and lo to the left. Thermostat faulty on the right side maybe?

 

I had a 1995 Integra. I don't remember for sure, but I don't think it started the AC automatically when you selected defrost.

We had a 1998 4-cyl Accord. When you select defrost, the AC lamp would light up, but then you could switch it off.

We had a 2003 4-cyl Accord. When you select defrost, the AC lamp would NOT light up, but the compressor DID begin cycling. And you couldn't switch it off.

So Honda/Acura has used different programming philosophies at different times.??

 

I tell you this...I think the whole system, the satnav, blue tooth and HVAC is unbelievably poor. I hate that touch screen thing. I like old fashioned ***** and proper buttons lol
Anyway whatever the quirks of HVAC, I have a fault of some kind somewhere and may yet end up at the dealer for a diagnostic check.
I had my Honda upgraded for performance. Its about 200 bhp Brilliant, so Ill persevere and get the heat fixed