Much like Sabarimala, Achankovil is located deep inside the Kerala side of western ghats forest. However Achankovil is accessible by a motorable road.
There are two routes to reach, Achankovil, one from Kerala side and the other from Tamilnadu side. The road from Kerala side connects Achankovil with Punalur, a major town about 45km southwest of Achankovil.
The route is like this: Punalur --> Alimukku --> Karavoor --> Mullumala --> Achankovil (45km)
Talking about this route, the first 20 km or so the road is in good condition, and it is mostly through villages and rubber plantations. Then the road condition progressively diorite as it enters passes through the forest. The last 10 to 15 km through the thick of the forest is a hard drive, the typical mud track, . Once inside the forest , the Achankovil river appears by the side of the road. The road will trace the river till you reach Achankovil village. The river is an easy guide to assure that you are on the right path inside the forest.
This is not a road frequented by other vehicles other than a few jeeps, the forest department vehicles and an odd KSRTC bus. And needless to say you may encounter wild elephants on the way. If you are not experienced in driving through forests, do not take this route to Achankovil. Instead head to Shenkottai and take the Shenkotta to Achankovil route via Panpozhi and Kumbhavurutty. ( Punalur - 50km -> Shenkottai -25km-> Achankovil )
Having said that, during the Sabarimala pilgrimage season, this route is pretty well used by the pilgrims to Sabarimala.
By the way KSRTC operates a few daily trips to Achankovil from Punalur, via both Shenkottai (fast passenger service) and Mullumala (ordinary service). The last bus from Achankovil leaves for Punalur (via Shenkottai) by 5.30pm. Note that the temple opens for evening darshan at 5pm. So hurry up if you have to catch that evening bus after the darshan. The bus leaves from the ground in front of the temple.
At Achankovil, mobile connectivity is good. But that can't be said when you cross the forest.
Monsoon hits Kerala coast first before its sweeps its way up through the Indian subcontinent.