You won't fix it yourself unless you can understand what everything does. Before you had the AC installed the HRV was interconnected to your furnace/airhandler fan. The a/c guys tied into this same system. When your tstat calls for a/c, an inter connection in the tstat brings the air handler fan on also. What is happening to you is it is back feeding so when you turn on the HRV, the a/c turns on as well. This is very bad. To verify if i'm right, turn on your hrv and if the a/c is on, flip the fan switch on the tstat to "on". The a/c should turn off. At best it will cost a boat load of power. At worst it will ruin the compressor. Let the a/c guys know and they will likely fix it up for you.

It is impossible for the condencer fan motor to run without the compressor. It runs on the same contactor. Though there is an internal overload that can shut the compressor down for heat/over amp issues.

Well you must be a HVAC installer as you were right. If the fan is going on the a/c unit after I turn on the Air exchanger and I turn the fan from auto to on, the fan does shut off. I am assuming this is a simple fix and it shouldn't cost me very much?

I wouldnt be quick to call it simple and cheap is a relative term. It would take me a relay and service call, shy of 200 would be a guess. A reputable company in Calgary would likely be just over 200. A guy that scratches his head lots and lets the smoke out of electronic boards could cost a thousand.

Do you have any electrician friends? Any experienced electrician should be able to help you out.
However, you now know the fan doesn't go on with the exchanger when the selection is made to "on" instead of "auto" so as long as everything still works correctly when the furnace or AC is working along with the exchanger, just leave the selection where it is.

A Psc fan running steady will eat $200 in 3 months with today's power costs.
If you have an ecm motor ( commonly called "DC" or "variable speed" it might take 6 months. Fixing it will be far cheaper.

This is an Hvac issue and we deal with it all the time. The a/c guys should have seen wires and fixed it when they installed it.

I don't use the air exchanger very often which is why I didnt notice this happening until years after the ac was installed. I just thought it might help my heat differential from top floor to bottom floor in the summer hence how I found out it was doing it.

I may have a look myself and see what is up in there.

Yep, this is totally accurate.

It sounds like the backfeeding thing as mentioned above. The original intent was to turn the exchanged on automatically when the A/C was run. But the opposite is also true.

You could have already done some serious damage to your A/C condensing unit if you've had the cover on. And besides, it's costing the same amount of money to run it right now as if it was the middle of summer, since the A/C and exchanger are both running at the same time.

I would call in a qualified HVAC person ASAP before any further damage is done.

EDIT: You may need to/want to invest in a good thermostat (I.E. Honeywell Vision Pro) that has a separate programmable output for the exchanger.

I don't think any damage is done as I have never really used the exchanger. It's on a manual switch which is almost always left off. We actually turned it off right by the furnace for most of it as we had little fingers going around turning on random switches in the house and we didn't want them to turn on the air exchanger. I am just finally realizing that maybe I should use it more and have come accross this problem.

Sounds like a wiring issue. Look inside the furnace, there should be 2 wires from the hrv to furnace, 2 from a/c to furnace and 3,4or5 from T stat to furnace. From the hrv to furnace one wire should go from the r terminal and one wire should go to the g terminal. If this wire went to the y terminal by accidient, this is the problem you would have. The wire to the Ac should go from the c terminal and one from the y terminal. If this wire was accidiently ran to the g terminal, same problem would happen. As well if this was the case, Ac would run if you switched the furnace to fan on position.