I had a similar problem recently, and searched around on TW. It seems there is a known issue among Toyotas in general, where the A/C Fan Clutch relay goes out intermittently.
This is usually remedied by turning the A/C off and back on, but a replacement relay may be necessary.
Here's some good info. from another thread:
Originally Posted by buddywh1
To follow up...I couldn't find a replacement relay at pepboys or autozone
...and I'm not ready to pay the $90 I hear Toyota is charging for one SOOOOooo...
I swapped the TOWING TAIL lights relay with it since I'm not towing anything right now. A/C works just fine, but it had only done the b blinking thing twice before so I suppose I'll never know for certain if that was it.
But...for anyone who'd be interested...this relay (the A/C clutch control relay, part no 90987-02028) is a REAL common problem for Toyota's. For some reason Toyota dealers want to charge heinous price for it, and it's just a SPST 12 volt relay using industry standard pin-outs and form. Mazda sells one that works just fine...their p/no is B115. If I can't find one for the normal price of $15 or so I'll be looking for a Mazda dealer.
Originally Posted by RCBS
Thepartsbin.com has a relay referred to as "AC fan clutch relay" for 17.95 ea. Their part number is W0133-1762256. its a Denso relay.