Just changed coolant on my cx5 and no heat now despite following instructions.
In order to bleed the air, on the service manual it says to run at 2500 rpm for 5 minutes, then 3000 for 5 seconds. I should do that after I fill up the reserve tank and tighten the radiator cap. Correct?
And I did.

Also saw somewhere can't remember where, to turn the heat on all the way and wait until you feel hot air come through. No hot air after 30 mins.
What should I do to fix this

 

To me it sounds like you might have disturbed the heater core and now its clogged with chunks. When I did mine I performed a flush first then rain it with distilled water after the flush then drained again and then finally filled it with clean fluid. How did you do it? It sounds like its bypassing the heater core. Is the engine temp normal?

 

I opened the petcock, and drained it. Also opened the radiator cap so it drained better. Once it stopped dripping, I poured distilled water in the radiator and let it drain. So basically just a rinse. Once all the distilled water drained and stopped dripping, close the petcock, fill the radiator to top, and the reservoir to full mark.

Close radiator & reservoir then 2500 rpm for close to 5 mins, 3000 rpm 5 seconds.
NOTE: that was yesterday & the air was luke warm despite being set to max setting. Also when I drained the coolant, it didn't look dirty or abnormal.

TODAY:
The coolant was lower than where it was yesterday.
I tried bleeding the air out by idling and setting heat to max. And squizing the hose, I was able to get some bubbles but not a lot. Air still luke warm.

 

Ok its not air in the cooling system . First while it is a service shown the fact remains that your engine and it cooling system technically does not need it done unless it was a dry system which yours was not. . That is not what is causing your proble at any rate.

 

Not sure what else to think. Haven't had any issue prior to changing coolant. I decided to change (drain and fill) the coolant because it was low not because there was any issue.

 

This statement is always and often posted by DIY with many services. The key point is that it was not a problem before you did the service. ergo you did something wrong or caused by the action of doing another problem or acerbated an existing one.

The thing to do is go back over every step you did. If you can without skipping and assuming you think you did that correctly?
I personal perform a couple dozen complete cooling syst replacements and service of the cooling system each year can say I have had to "burb" the system ever. For one thing most all thermostat (hopefully you did not damge the working thermostat in your cooling system service) have a jiggle valve that does that automatically. Now those jiggle vales are sorta new only been used for about 40 years or more ? There are however a few heads on some platform that the casting would cause steam pockets and over heating after a cooling system flush and replacement that you did need to either gravity burp the system. The most stubborn of cooling system if you start the engine run to operating temperature. Then when you can safety remove the radiator cap and have the front of the car up on ramps letting it set a few hour or overnight should take care of the air problem.
Mazda head do not have casting issues in the water jacket area's that have ever been known or posted that I am aware of? But I don't follow every possible service problem and tend to learn more from servicing customers cars what is and is not usually. or actually reading about them and then trying to decide if they are good or just another DIY fail! .

 

Im convinced that the heater core is clogged. Can you explain why draining the radiator might cause the heater core to get clogged?

 

This is a common problem when a cooling system is flushed without doing a proper procedure and check before re-filing with coolant dating back to the 70's.

One thing we (mechanic and or Auto techs) take notice of is the color and water comes out during a colling system flush. If there are any debris then we know that there could be contaminated heater core, hosses (there are several on most Mazda's) and or water controlling valves. Also the use of chemical flushing should be used. The better one have sever steppes which include introduction and flushing after their adding following the service instruction set by the chemical supplier. Single stage or stepped flushing chemical IMHO don't do as well as multiple steeped flushing chemicals. But that may only be my opinion I have never really done a back to bac test as it would be very difficult to find to vehicles with exactly the same condition for an accurate test comparison..

 

Any idea which hoses I would need to disconnect? I think the top right is the inlet because it was hot to the touch. Not sure what other hoses to disconnect to do a heater core flush

 

heater core is on the right side of your picture